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[PATCH] soc: qcom: gsbi: fix double disable caused by devm

by Haotian Zhang

In the commit referenced by the Fixes tag, devm_clk_get_enabled() was introduced to replace devm_clk_get() and clk_prepare_enable(). While the clk_disable_unprepare() call in the error path was correctly removed, the one in the remove function was overlooked, leading to a double disable issue. Remove the redundant clk_disable_unprepare() call from gsbi_remove() to fix this issue. Since all resources are now managed by devres and will be automatically released, the remove function serves no purpose and can be deleted entirely. Fixes: 489d7a8cc286 ("soc: qcom: use devm_clk_get_enabled() in gsbi_probe()") Signed-off-by: Haotian Zhang <vulab(a)iscas.ac.cn> --- drivers/soc/qcom/qcom_gsbi.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/drivers/soc/qcom/qcom_gsbi.c b/drivers/soc/qcom/qcom_gsbi.c index 8f1158e0c631..a25d1de592f0 100644 --- a/drivers/soc/qcom/qcom_gsbi.c +++ b/drivers/soc/qcom/qcom_gsbi.c @@ -212,13 +212,6 @@ static int gsbi_probe(struct platform_device *pdev) return of_platform_populate(node, NULL, NULL, &pdev->dev); } -static void gsbi_remove(struct platform_device *pdev) -{ - struct gsbi_info *gsbi = platform_get_drvdata(pdev); - - clk_disable_unprepare(gsbi->hclk); -} - static const struct of_device_id gsbi_dt_match[] = { { .compatible = "qcom,gsbi-v1.0.0", }, { }, @@ -232,7 +225,6 @@ static struct platform_driver gsbi_driver = { .of_match_table = gsbi_dt_match, }, .probe = gsbi_probe, - .remove = gsbi_remove, }; module_platform_driver(gsbi_driver); -- 2.25.1

1 week, 4 days

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[PATCH 0/2] Kconfig fixes for QCOM clk drivers when targeting ARCH=arm

by Nathan Chancellor

Hi all, This series resolves two new Kconfig warnings that I see in my test framework from an ARM configuration getting bumped to 6.17 and enabling these configurations in the process. --- Nathan Chancellor (2): clk: qcom: Fix SM_VIDEOCC_6350 dependencies clk: qcom: Fix dependencies of QCS_{DISP,GPU,VIDEO}CC_615 drivers/clk/qcom/Kconfig | 4 ++++ 1 file changed, 4 insertions(+) --- base-commit: 30bf3ec8cb6b2d2e2f8715388395cbd27cbe4fc9 change-id: 20250930-clk-qcom-kconfig-fixes-arm-3611dec03c3e Best regards, -- Nathan Chancellor <nathan(a)kernel.org>

1 week, 4 days

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[PATCH v2] usb: renesas_usbhs: Fix synchronous external abort on unbind

by Claudiu

From: Claudiu Beznea <claudiu.beznea.uj(a)bp.renesas.com> A synchronous external abort occurs on the Renesas RZ/G3S SoC if unbind is executed after the configuration sequence described above: modprobe usb_f_ecm modprobe libcomposite modprobe configfs cd /sys/kernel/config/usb_gadget mkdir -p g1 cd g1 echo "0x1d6b" > idVendor echo "0x0104" > idProduct mkdir -p strings/0x409 echo "0123456789" > strings/0x409/serialnumber echo "Renesas." > strings/0x409/manufacturer echo "Ethernet Gadget" > strings/0x409/product mkdir -p functions/ecm.usb0 mkdir -p configs/c.1 mkdir -p configs/c.1/strings/0x409 echo "ECM" > configs/c.1/strings/0x409/configuration if [ ! -L configs/c.1/ecm.usb0 ]; then ln -s functions/ecm.usb0 configs/c.1 fi echo 11e20000.usb > UDC echo 11e20000.usb > /sys/bus/platform/drivers/renesas_usbhs/unbind The displayed trace is as follows: Internal error: synchronous external abort: 0000000096000010 [#1] SMP CPU: 0 UID: 0 PID: 188 Comm: sh Tainted: G M 6.17.0-rc7-next-20250922-00010-g41050493b2bd #55 PREEMPT Tainted: [M]=MACHINE_CHECK Hardware name: Renesas SMARC EVK version 2 based on r9a08g045s33 (DT) pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : usbhs_sys_function_pullup+0x10/0x40 [renesas_usbhs] lr : usbhsg_update_pullup+0x3c/0x68 [renesas_usbhs] sp : ffff8000838b3920 x29: ffff8000838b3920 x28: ffff00000d585780 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: ffff00000c3e3810 x23: ffff00000d5e5c80 x22: ffff00000d5e5d40 x21: 0000000000000000 x20: 0000000000000000 x19: ffff00000d5e5c80 x18: 0000000000000020 x17: 2e30303230316531 x16: 312d7968703a7968 x15: 3d454d414e5f4344 x14: 000000000000002c x13: 0000000000000000 x12: 0000000000000000 x11: ffff00000f358f38 x10: ffff00000f358db0 x9 : ffff00000b41f418 x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : fefefeff6364626d x5 : 8080808000000000 x4 : 000000004b5ccb9d x3 : 0000000000000000 x2 : 0000000000000000 x1 : ffff800083790000 x0 : ffff00000d5e5c80 Call trace: usbhs_sys_function_pullup+0x10/0x40 [renesas_usbhs] (P) usbhsg_pullup+0x4c/0x7c [renesas_usbhs] usb_gadget_disconnect_locked+0x48/0xd4 gadget_unbind_driver+0x44/0x114 device_remove+0x4c/0x80 device_release_driver_internal+0x1c8/0x224 device_release_driver+0x18/0x24 bus_remove_device+0xcc/0x10c device_del+0x14c/0x404 usb_del_gadget+0x88/0xc0 usb_del_gadget_udc+0x18/0x30 usbhs_mod_gadget_remove+0x24/0x44 [renesas_usbhs] usbhs_mod_remove+0x20/0x30 [renesas_usbhs] usbhs_remove+0x98/0xdc [renesas_usbhs] platform_remove+0x20/0x30 device_remove+0x4c/0x80 device_release_driver_internal+0x1c8/0x224 device_driver_detach+0x18/0x24 unbind_store+0xb4/0xb8 drv_attr_store+0x24/0x38 sysfs_kf_write+0x7c/0x94 kernfs_fop_write_iter+0x128/0x1b8 vfs_write+0x2ac/0x350 ksys_write+0x68/0xfc __arm64_sys_write+0x1c/0x28 invoke_syscall+0x48/0x110 el0_svc_common.constprop.0+0xc0/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x34/0xf0 el0t_64_sync_handler+0xa0/0xe4 el0t_64_sync+0x198/0x19c Code: 7100003f 1a9f07e1 531c6c22 f9400001 (79400021) ---[ end trace 0000000000000000 ]--- note: sh[188] exited with irqs disabled note: sh[188] exited with preempt_count 1 The issue occurs because usbhs_sys_function_pullup(), which accesses the IP registers, is executed after the USBHS clocks have been disabled. The problem is reproducible on the Renesas RZ/G3S SoC starting with the addition of module stop in the clock enable/disable APIs. With module stop functionality enabled, a bus error is expected if a master accesses a module whose clock has been stopped and module stop activated. Disable the IP clocks at the end of remove. Cc: stable(a)vger.kernel.org Fixes: f1407d5c6624 ("usb: renesas_usbhs: Add Renesas USBHS common code") Signed-off-by: Claudiu Beznea <claudiu.beznea.uj(a)bp.renesas.com> --- Changes in v2: - moved usbhsc_clk_put() before pm_runtime_disable() Patch was tested with continuous unbind/bind and the configuration sequence described above on the boards with the following device trees: - r8a774a1-hihope-rzg2m-ex.dts - r8a774b1-hihope-rzg2n-ex.dts - r8a774e1-hihope-rzg2h-ex.dts - r9a07g043u11-smarc.dts - r9a07g044c2-smarc.dts - r9a07g044l2-smarc.dts - r9a07g054l2-smarc.dts drivers/usb/renesas_usbhs/common.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c index 8f536f2c500f..dc2fec9168b7 100644 --- a/drivers/usb/renesas_usbhs/common.c +++ b/drivers/usb/renesas_usbhs/common.c @@ -813,18 +813,18 @@ static void usbhs_remove(struct platform_device *pdev) flush_delayed_work(&priv->notify_hotplug_work); - /* power off */ - if (!usbhs_get_dparam(priv, runtime_pwctrl)) - usbhsc_power_ctrl(priv, 0); - - pm_runtime_disable(&pdev->dev); - usbhs_platform_call(priv, hardware_exit, pdev); - usbhsc_clk_put(priv); reset_control_assert(priv->rsts); usbhs_mod_remove(priv); usbhs_fifo_remove(priv); usbhs_pipe_remove(priv); + + /* power off */ + if (!usbhs_get_dparam(priv, runtime_pwctrl)) + usbhsc_power_ctrl(priv, 0); + + usbhsc_clk_put(priv); + pm_runtime_disable(&pdev->dev); } static int usbhsc_suspend(struct device *dev) -- 2.43.0

1 week, 4 days

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[REGRESSION] stable-rc/linux-5.10.y: (build) implicit declaration of function ‘of_get_cpu_hwid’; did you mean ‘...

by KernelCI bot

Hello, New build issue found on stable-rc/linux-5.10.y: --- implicit declaration of function ‘of_get_cpu_hwid’; did you mean ‘of_get_cpu_node’? [-Werror=implicit-function-declaration] in arch/riscv/kernel/cpu.o (arch/riscv/kernel/cpu.c) [logspec:kbuild,kbuild.compiler.error] --- - dashboard: https://d.kernelci.org/i/maestro:aa2fc1f4fdbcaf13e029f04263806fde636d74fd - giturl: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git - commit HEAD: 7288ed51fe2777d083b6cb13bd2d18f368fa425d Log excerpt: ===================================================== arch/riscv/kernel/cpu.c:24:33: error: implicit declaration of function ‘of_get_cpu_hwid’; did you mean ‘of_get_cpu_node’? [-Werror=implicit-function-declaration] 24 | *hart = (unsigned long) of_get_cpu_hwid(node, 0); | ^~~~~~~~~~~~~~~ | of_get_cpu_node AR init/built-in.a CC kernel/locking/mutex.o CC arch/riscv/mm/fault.o cc1: some warnings being treated as errors ===================================================== # Builds where the incident occurred: ## defconfig on (riscv): - compiler: gcc-12 - config: https://files.kernelci.org/kbuild-gcc-12-riscv-68ff66e51198e7d4c92ca056/.co… - dashboard: https://d.kernelci.org/build/maestro:68ff66e51198e7d4c92ca056 #kernelci issue maestro:aa2fc1f4fdbcaf13e029f04263806fde636d74fd Reported-by: kernelci.org bot <bot(a)kernelci.org> -- This is an experimental report format. Please send feedback in! Talk to us at kernelci(a)lists.linux.dev Made with love by the KernelCI team - https://kernelci.org

1 week, 4 days

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[REGRESSION] stable-rc/linux-5.15.y: (build) unused variable ‘ext_end’ [-Wunused-variable] in arch/riscv/kernel...

by KernelCI bot

Hello, New build issue found on stable-rc/linux-5.15.y: --- unused variable ‘ext_end’ [-Wunused-variable] in arch/riscv/kernel/cpu.o (arch/riscv/kernel/cpufeature.c) [logspec:kbuild,kbuild.compiler.warning] --- - dashboard: https://d.kernelci.org/i/maestro:5135288c90855e0205f0a76b012c159c9f2e4f97 - giturl: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git - commit HEAD: 2e86ed6526626d22b225d03a7faf8bd09dca2a5b Log excerpt: ===================================================== arch/riscv/kernel/cpufeature.c:107:37: warning: unused variable ‘ext_end’ [-Wunused-variable] 107 | const char *ext_end = isa; | ^~~~~~~ arch/riscv/kernel/cpu.c: In function ‘riscv_of_processor_hartid’: arch/riscv/kernel/cpu.c:24:33: error: implicit declaration of function ‘of_get_cpu_hwid’; did you mean ‘of_get_cpu_node’? [-Werror=implicit-function-declaration] 24 | *hart = (unsigned long) of_get_cpu_hwid(node, 0); | ^~~~~~~~~~~~~~~ | of_get_cpu_node cc1: some warnings being treated as errors ===================================================== # Builds where the incident occurred: ## defconfig on (riscv): - compiler: gcc-12 - config: https://files.kernelci.org/kbuild-gcc-12-riscv-68ff67651198e7d4c92ca10f/.co… - dashboard: https://d.kernelci.org/build/maestro:68ff67651198e7d4c92ca10f ## nommu_k210_defconfig on (riscv): - compiler: gcc-12 - config: https://files.kernelci.org/kbuild-gcc-12-riscv-nommu_k210_defconfig-68ff66e… - dashboard: https://d.kernelci.org/build/maestro:68ff66e91198e7d4c92ca077 #kernelci issue maestro:5135288c90855e0205f0a76b012c159c9f2e4f97 Reported-by: kernelci.org bot <bot(a)kernelci.org> -- This is an experimental report format. Please send feedback in! Talk to us at kernelci(a)lists.linux.dev Made with love by the KernelCI team - https://kernelci.org

1 week, 4 days

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FAILED: patch "[PATCH] devcoredump: Fix circular locking dependency with" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x a91c8096590bd7801a26454789f2992094fe36da # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025102625-cringing-unstuck-790a@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From a91c8096590bd7801a26454789f2992094fe36da Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst <dev(a)lankhorst.se> Date: Wed, 23 Jul 2025 16:24:16 +0200 Subject: [PATCH] devcoredump: Fix circular locking dependency with devcd->mutex. The original code causes a circular locking dependency found by lockdep. ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc6-lgci-xe-xe-pw-151626v3+ #1 Tainted: G S U ------------------------------------------------------ xe_fault_inject/5091 is trying to acquire lock: ffff888156815688 ((work_completion)(&(&devcd->del_wk)->work)){+.+.}-{0:0}, at: __flush_work+0x25d/0x660 but task is already holding lock: ffff888156815620 (&devcd->mutex){+.+.}-{3:3}, at: dev_coredump_put+0x3f/0xa0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&devcd->mutex){+.+.}-{3:3}: mutex_lock_nested+0x4e/0xc0 devcd_data_write+0x27/0x90 sysfs_kf_bin_write+0x80/0xf0 kernfs_fop_write_iter+0x169/0x220 vfs_write+0x293/0x560 ksys_write+0x72/0xf0 __x64_sys_write+0x19/0x30 x64_sys_call+0x2bf/0x2660 do_syscall_64+0x93/0xb60 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #1 (kn->active#236){++++}-{0:0}: kernfs_drain+0x1e2/0x200 __kernfs_remove+0xae/0x400 kernfs_remove_by_name_ns+0x5d/0xc0 remove_files+0x54/0x70 sysfs_remove_group+0x3d/0xa0 sysfs_remove_groups+0x2e/0x60 device_remove_attrs+0xc7/0x100 device_del+0x15d/0x3b0 devcd_del+0x19/0x30 process_one_work+0x22b/0x6f0 worker_thread+0x1e8/0x3d0 kthread+0x11c/0x250 ret_from_fork+0x26c/0x2e0 ret_from_fork_asm+0x1a/0x30 -> #0 ((work_completion)(&(&devcd->del_wk)->work)){+.+.}-{0:0}: __lock_acquire+0x1661/0x2860 lock_acquire+0xc4/0x2f0 __flush_work+0x27a/0x660 flush_delayed_work+0x5d/0xa0 dev_coredump_put+0x63/0xa0 xe_driver_devcoredump_fini+0x12/0x20 [xe] devm_action_release+0x12/0x30 release_nodes+0x3a/0x120 devres_release_all+0x8a/0xd0 device_unbind_cleanup+0x12/0x80 device_release_driver_internal+0x23a/0x280 device_driver_detach+0x14/0x20 unbind_store+0xaf/0xc0 drv_attr_store+0x21/0x50 sysfs_kf_write+0x4a/0x80 kernfs_fop_write_iter+0x169/0x220 vfs_write+0x293/0x560 ksys_write+0x72/0xf0 __x64_sys_write+0x19/0x30 x64_sys_call+0x2bf/0x2660 do_syscall_64+0x93/0xb60 entry_SYSCALL_64_after_hwframe+0x76/0x7e other info that might help us debug this: Chain exists of: (work_completion)(&(&devcd->del_wk)->work) --> kn->active#236 --> &devcd->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&devcd->mutex); lock(kn->active#236); lock(&devcd->mutex); lock((work_completion)(&(&devcd->del_wk)->work)); *** DEADLOCK *** 5 locks held by xe_fault_inject/5091: #0: ffff8881129f9488 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x72/0xf0 #1: ffff88810c755078 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x123/0x220 #2: ffff8881054811a0 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x55/0x280 #3: ffff888156815620 (&devcd->mutex){+.+.}-{3:3}, at: dev_coredump_put+0x3f/0xa0 #4: ffffffff8359e020 (rcu_read_lock){....}-{1:2}, at: __flush_work+0x72/0x660 stack backtrace: CPU: 14 UID: 0 PID: 5091 Comm: xe_fault_inject Tainted: G S U 6.16.0-rc6-lgci-xe-xe-pw-151626v3+ #1 PREEMPT_{RT,(lazy)} Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER Hardware name: Micro-Star International Co., Ltd. MS-7D25/PRO Z690-A DDR4(MS-7D25), BIOS 1.10 12/13/2021 Call Trace: <TASK> dump_stack_lvl+0x91/0xf0 dump_stack+0x10/0x20 print_circular_bug+0x285/0x360 check_noncircular+0x135/0x150 ? register_lock_class+0x48/0x4a0 __lock_acquire+0x1661/0x2860 lock_acquire+0xc4/0x2f0 ? __flush_work+0x25d/0x660 ? mark_held_locks+0x46/0x90 ? __flush_work+0x25d/0x660 __flush_work+0x27a/0x660 ? __flush_work+0x25d/0x660 ? trace_hardirqs_on+0x1e/0xd0 ? __pfx_wq_barrier_func+0x10/0x10 flush_delayed_work+0x5d/0xa0 dev_coredump_put+0x63/0xa0 xe_driver_devcoredump_fini+0x12/0x20 [xe] devm_action_release+0x12/0x30 release_nodes+0x3a/0x120 devres_release_all+0x8a/0xd0 device_unbind_cleanup+0x12/0x80 device_release_driver_internal+0x23a/0x280 ? bus_find_device+0xa8/0xe0 device_driver_detach+0x14/0x20 unbind_store+0xaf/0xc0 drv_attr_store+0x21/0x50 sysfs_kf_write+0x4a/0x80 kernfs_fop_write_iter+0x169/0x220 vfs_write+0x293/0x560 ksys_write+0x72/0xf0 __x64_sys_write+0x19/0x30 x64_sys_call+0x2bf/0x2660 do_syscall_64+0x93/0xb60 ? __f_unlock_pos+0x15/0x20 ? __x64_sys_getdents64+0x9b/0x130 ? __pfx_filldir64+0x10/0x10 ? do_syscall_64+0x1a2/0xb60 ? clear_bhb_loop+0x30/0x80 ? clear_bhb_loop+0x30/0x80 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x76e292edd574 Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 80 3d d5 ea 0e 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89 RSP: 002b:00007fffe247a828 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000076e292edd574 RDX: 000000000000000c RSI: 00006267f6306063 RDI: 000000000000000b RBP: 000000000000000c R08: 000076e292fc4b20 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00006267f6306063 R13: 000000000000000b R14: 00006267e6859c00 R15: 000076e29322a000 </TASK> xe 0000:03:00.0: [drm] Xe device coredump has been deleted. Fixes: 01daccf74832 ("devcoredump : Serialize devcd_del work") Cc: Mukesh Ojha <quic_mojha(a)quicinc.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: Johannes Berg <johannes(a)sipsolutions.net> Cc: Rafael J. Wysocki <rafael(a)kernel.org> Cc: Danilo Krummrich <dakr(a)kernel.org> Cc: linux-kernel(a)vger.kernel.org Cc: stable(a)vger.kernel.org # v6.1+ Signed-off-by: Maarten Lankhorst <dev(a)lankhorst.se> Cc: Matthew Brost <matthew.brost(a)intel.com> Acked-by: Mukesh Ojha <mukesh.ojha(a)oss.qualcomm.com> Link: https://lore.kernel.org/r/20250723142416.1020423-1-dev@lankhorst.se Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c index 37faf6156d7c..55bdc7f5e59d 100644 --- a/drivers/base/devcoredump.c +++ b/drivers/base/devcoredump.c @@ -23,50 +23,46 @@ struct devcd_entry { void *data; size_t datalen; /* - * Here, mutex is required to serialize the calls to del_wk work between - * user/kernel space which happens when devcd is added with device_add() - * and that sends uevent to user space. User space reads the uevents, - * and calls to devcd_data_write() which try to modify the work which is - * not even initialized/queued from devcoredump. + * There are 2 races for which mutex is required. * + * The first race is between device creation and userspace writing to + * schedule immediately destruction. * + * This race is handled by arming the timer before device creation, but + * when device creation fails the timer still exists. * - * cpu0(X) cpu1(Y) + * To solve this, hold the mutex during device_add(), and set + * init_completed on success before releasing the mutex. * - * dev_coredump() uevent sent to user space - * device_add() ======================> user space process Y reads the - * uevents writes to devcd fd - * which results into writes to + * That way the timer will never fire until device_add() is called, + * it will do nothing if init_completed is not set. The timer is also + * cancelled in that case. * - * devcd_data_write() - * mod_delayed_work() - * try_to_grab_pending() - * timer_delete() - * debug_assert_init() - * INIT_DELAYED_WORK() - * schedule_delayed_work() - * - * - * Also, mutex alone would not be enough to avoid scheduling of - * del_wk work after it get flush from a call to devcd_free() - * mentioned as below. - * - * disabled_store() - * devcd_free() - * mutex_lock() devcd_data_write() - * flush_delayed_work() - * mutex_unlock() - * mutex_lock() - * mod_delayed_work() - * mutex_unlock() - * So, delete_work flag is required. + * The second race involves multiple parallel invocations of devcd_free(), + * add a deleted flag so only 1 can call the destructor. */ struct mutex mutex; - bool delete_work; + bool init_completed, deleted; struct module *owner; ssize_t (*read)(char *buffer, loff_t offset, size_t count, void *data, size_t datalen); void (*free)(void *data); + /* + * If nothing interferes and device_add() was returns success, + * del_wk will destroy the device after the timer fires. + * + * Multiple userspace processes can interfere in the working of the timer: + * - Writing to the coredump will reschedule the timer to run immediately, + * if still armed. + * + * This is handled by using "if (cancel_delayed_work()) { + * schedule_delayed_work() }", to prevent re-arming after having + * been previously fired. + * - Writing to /sys/class/devcoredump/disabled will destroy the + * coredump synchronously. + * This is handled by using disable_delayed_work_sync(), and then + * checking if deleted flag is set with &devcd->mutex held. + */ struct delayed_work del_wk; struct device *failing_dev; }; @@ -95,14 +91,27 @@ static void devcd_dev_release(struct device *dev) kfree(devcd); } +static void __devcd_del(struct devcd_entry *devcd) +{ + devcd->deleted = true; + device_del(&devcd->devcd_dev); + put_device(&devcd->devcd_dev); +} + static void devcd_del(struct work_struct *wk) { struct devcd_entry *devcd; + bool init_completed; devcd = container_of(wk, struct devcd_entry, del_wk.work); - device_del(&devcd->devcd_dev); - put_device(&devcd->devcd_dev); + /* devcd->mutex serializes against dev_coredumpm_timeout */ + mutex_lock(&devcd->mutex); + init_completed = devcd->init_completed; + mutex_unlock(&devcd->mutex); + + if (init_completed) + __devcd_del(devcd); } static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj, @@ -122,12 +131,12 @@ static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj, struct device *dev = kobj_to_dev(kobj); struct devcd_entry *devcd = dev_to_devcd(dev); - mutex_lock(&devcd->mutex); - if (!devcd->delete_work) { - devcd->delete_work = true; - mod_delayed_work(system_wq, &devcd->del_wk, 0); - } - mutex_unlock(&devcd->mutex); + /* + * Although it's tempting to use mod_delayed work here, + * that will cause a reschedule if the timer already fired. + */ + if (cancel_delayed_work(&devcd->del_wk)) + schedule_delayed_work(&devcd->del_wk, 0); return count; } @@ -151,11 +160,21 @@ static int devcd_free(struct device *dev, void *data) { struct devcd_entry *devcd = dev_to_devcd(dev); + /* + * To prevent a race with devcd_data_write(), disable work and + * complete manually instead. + * + * We cannot rely on the return value of + * disable_delayed_work_sync() here, because it might be in the + * middle of a cancel_delayed_work + schedule_delayed_work pair. + * + * devcd->mutex here guards against multiple parallel invocations + * of devcd_free(). + */ + disable_delayed_work_sync(&devcd->del_wk); mutex_lock(&devcd->mutex); - if (!devcd->delete_work) - devcd->delete_work = true; - - flush_delayed_work(&devcd->del_wk); + if (!devcd->deleted) + __devcd_del(devcd); mutex_unlock(&devcd->mutex); return 0; } @@ -179,12 +198,10 @@ static ssize_t disabled_show(const struct class *class, const struct class_attri * put_device() <- last reference * error = fn(dev, data) devcd_dev_release() * devcd_free(dev, data) kfree(devcd) - * mutex_lock(&devcd->mutex); * * * In the above diagram, it looks like disabled_store() would be racing with parallelly - * running devcd_del() and result in memory abort while acquiring devcd->mutex which - * is called after kfree of devcd memory after dropping its last reference with + * running devcd_del() and result in memory abort after dropping its last reference with * put_device(). However, this will not happens as fn(dev, data) runs * with its own reference to device via klist_node so it is not its last reference. * so, above situation would not occur. @@ -374,7 +391,7 @@ void dev_coredumpm_timeout(struct device *dev, struct module *owner, devcd->read = read; devcd->free = free; devcd->failing_dev = get_device(dev); - devcd->delete_work = false; + devcd->deleted = false; mutex_init(&devcd->mutex); device_initialize(&devcd->devcd_dev); @@ -383,8 +400,14 @@ void dev_coredumpm_timeout(struct device *dev, struct module *owner, atomic_inc_return(&devcd_count)); devcd->devcd_dev.class = &devcd_class; - mutex_lock(&devcd->mutex); dev_set_uevent_suppress(&devcd->devcd_dev, true); + + /* devcd->mutex prevents devcd_del() completing until init finishes */ + mutex_lock(&devcd->mutex); + devcd->init_completed = false; + INIT_DELAYED_WORK(&devcd->del_wk, devcd_del); + schedule_delayed_work(&devcd->del_wk, timeout); + if (device_add(&devcd->devcd_dev)) goto put_device; @@ -401,13 +424,20 @@ void dev_coredumpm_timeout(struct device *dev, struct module *owner, dev_set_uevent_suppress(&devcd->devcd_dev, false); kobject_uevent(&devcd->devcd_dev.kobj, KOBJ_ADD); - INIT_DELAYED_WORK(&devcd->del_wk, devcd_del); - schedule_delayed_work(&devcd->del_wk, timeout); + + /* + * Safe to run devcd_del() now that we are done with devcd_dev. + * Alternatively we could have taken a ref on devcd_dev before + * dropping the lock. + */ + devcd->init_completed = true; mutex_unlock(&devcd->mutex); return; put_device: - put_device(&devcd->devcd_dev); mutex_unlock(&devcd->mutex); + cancel_delayed_work_sync(&devcd->del_wk); + put_device(&devcd->devcd_dev); + put_module: module_put(owner); free:

1 week, 4 days

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FAILED: patch "[PATCH] xfs: always warn about deprecated mount options" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 630785bfbe12c3ee3ebccd8b530a98d632b7e39d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025102617-untrimmed-ideally-b80b@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 630785bfbe12c3ee3ebccd8b530a98d632b7e39d Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" <djwong(a)kernel.org> Date: Tue, 21 Oct 2025 11:30:12 -0700 Subject: [PATCH] xfs: always warn about deprecated mount options The deprecation of the 'attr2' mount option in 6.18 wasn't entirely successful because nobody noticed that the kernel never printed a warning about attr2 being set in fstab if the only xfs filesystem is the root fs; the initramfs mounts the root fs with no mount options; and the init scripts only conveyed the fstab options by remounting the root fs. Fix this by making it complain all the time. Cc: stable(a)vger.kernel.org # v5.13 Fixes: 92cf7d36384b99 ("xfs: Skip repetitive warnings about mount options") Signed-off-by: Darrick J. Wong <djwong(a)kernel.org> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Reviewed-by: Carlos Maiolino <cmaiolino(a)redhat.com> Signed-off-by: Carlos Maiolino <cem(a)kernel.org> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 9d51186b24dd..c53f2edf92e7 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1379,16 +1379,25 @@ suffix_kstrtoull( static inline void xfs_fs_warn_deprecated( struct fs_context *fc, - struct fs_parameter *param, - uint64_t flag, - bool value) + struct fs_parameter *param) { - /* Don't print the warning if reconfiguring and current mount point - * already had the flag set + /* + * Always warn about someone passing in a deprecated mount option. + * Previously we wouldn't print the warning if we were reconfiguring + * and current mount point already had the flag set, but that was not + * the right thing to do. + * + * Many distributions mount the root filesystem with no options in the + * initramfs and rely on mount -a to remount the root fs with the + * options in fstab. However, the old behavior meant that there would + * never be a warning about deprecated mount options for the root fs in + * /etc/fstab. On a single-fs system, that means no warning at all. + * + * Compounding this problem are distribution scripts that copy + * /proc/mounts to fstab, which means that we can't remove mount + * options unless we're 100% sure they have only ever been advertised + * in /proc/mounts in response to explicitly provided mount options. */ - if ((fc->purpose & FS_CONTEXT_FOR_RECONFIGURE) && - !!(XFS_M(fc->root->d_sb)->m_features & flag) == value) - return; xfs_warn(fc->s_fs_info, "%s mount option is deprecated.", param->key); }

1 week, 4 days

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FAILED: patch "[PATCH] net: ravb: Enforce descriptor type ordering" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 5370c31e84b0e0999c7b5ff949f4e104def35584 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025102623-footless-outcast-b793@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 5370c31e84b0e0999c7b5ff949f4e104def35584 Mon Sep 17 00:00:00 2001 From: Lad Prabhakar <prabhakar.mahadev-lad.rj(a)bp.renesas.com> Date: Fri, 17 Oct 2025 16:18:29 +0100 Subject: [PATCH] net: ravb: Enforce descriptor type ordering MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Ensure the TX descriptor type fields are published in a safe order so the DMA engine never begins processing a descriptor chain before all descriptor fields are fully initialised. For multi-descriptor transmits the driver writes DT_FEND into the last descriptor and DT_FSTART into the first. The DMA engine begins processing when it observes DT_FSTART. Move the dma_wmb() barrier so it executes immediately after DT_FEND and immediately before writing DT_FSTART (and before DT_FSINGLE in the single-descriptor case). This guarantees that all prior CPU writes to the descriptor memory are visible to the device before DT_FSTART is seen. This avoids a situation where compiler/CPU reordering could publish DT_FSTART ahead of DT_FEND or other descriptor fields, allowing the DMA to start on a partially initialised chain and causing corrupted transmissions or TX timeouts. Such a failure was observed on RZ/G2L with an RT kernel as transmit queue timeouts and device resets. Fixes: 2f45d1902acf ("ravb: minimize TX data copying") Cc: stable(a)vger.kernel.org Co-developed-by: Fabrizio Castro <fabrizio.castro.jz(a)renesas.com> Signed-off-by: Fabrizio Castro <fabrizio.castro.jz(a)renesas.com> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj(a)bp.renesas.com> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas(a)ragnatech.se> Link: https://patch.msgid.link/20251017151830.171062-4-prabhakar.mahadev-lad.rj@b… Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c index 9d3bd65b85ff..044ee83c63bb 100644 --- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -2211,13 +2211,25 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev) skb_tx_timestamp(skb); } - /* Descriptor type must be set after all the above writes */ - dma_wmb(); + if (num_tx_desc > 1) { desc->die_dt = DT_FEND; desc--; + /* When using multi-descriptors, DT_FEND needs to get written + * before DT_FSTART, but the compiler may reorder the memory + * writes in an attempt to optimize the code. + * Use a dma_wmb() barrier to make sure DT_FEND and DT_FSTART + * are written exactly in the order shown in the code. + * This is particularly important for cases where the DMA engine + * is already running when we are running this code. If the DMA + * sees DT_FSTART without the corresponding DT_FEND it will enter + * an error condition. + */ + dma_wmb(); desc->die_dt = DT_FSTART; } else { + /* Descriptor type must be set after all the above writes */ + dma_wmb(); desc->die_dt = DT_FSINGLE; } ravb_modify(ndev, TCCR, TCCR_TSRQ0 << q, TCCR_TSRQ0 << q);

1 week, 4 days

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FAILED: patch "[PATCH] devcoredump: Fix circular locking dependency with" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x a91c8096590bd7801a26454789f2992094fe36da # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025102624-aspect-stumble-aea9@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From a91c8096590bd7801a26454789f2992094fe36da Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst <dev(a)lankhorst.se> Date: Wed, 23 Jul 2025 16:24:16 +0200 Subject: [PATCH] devcoredump: Fix circular locking dependency with devcd->mutex. The original code causes a circular locking dependency found by lockdep. ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc6-lgci-xe-xe-pw-151626v3+ #1 Tainted: G S U ------------------------------------------------------ xe_fault_inject/5091 is trying to acquire lock: ffff888156815688 ((work_completion)(&(&devcd->del_wk)->work)){+.+.}-{0:0}, at: __flush_work+0x25d/0x660 but task is already holding lock: ffff888156815620 (&devcd->mutex){+.+.}-{3:3}, at: dev_coredump_put+0x3f/0xa0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&devcd->mutex){+.+.}-{3:3}: mutex_lock_nested+0x4e/0xc0 devcd_data_write+0x27/0x90 sysfs_kf_bin_write+0x80/0xf0 kernfs_fop_write_iter+0x169/0x220 vfs_write+0x293/0x560 ksys_write+0x72/0xf0 __x64_sys_write+0x19/0x30 x64_sys_call+0x2bf/0x2660 do_syscall_64+0x93/0xb60 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #1 (kn->active#236){++++}-{0:0}: kernfs_drain+0x1e2/0x200 __kernfs_remove+0xae/0x400 kernfs_remove_by_name_ns+0x5d/0xc0 remove_files+0x54/0x70 sysfs_remove_group+0x3d/0xa0 sysfs_remove_groups+0x2e/0x60 device_remove_attrs+0xc7/0x100 device_del+0x15d/0x3b0 devcd_del+0x19/0x30 process_one_work+0x22b/0x6f0 worker_thread+0x1e8/0x3d0 kthread+0x11c/0x250 ret_from_fork+0x26c/0x2e0 ret_from_fork_asm+0x1a/0x30 -> #0 ((work_completion)(&(&devcd->del_wk)->work)){+.+.}-{0:0}: __lock_acquire+0x1661/0x2860 lock_acquire+0xc4/0x2f0 __flush_work+0x27a/0x660 flush_delayed_work+0x5d/0xa0 dev_coredump_put+0x63/0xa0 xe_driver_devcoredump_fini+0x12/0x20 [xe] devm_action_release+0x12/0x30 release_nodes+0x3a/0x120 devres_release_all+0x8a/0xd0 device_unbind_cleanup+0x12/0x80 device_release_driver_internal+0x23a/0x280 device_driver_detach+0x14/0x20 unbind_store+0xaf/0xc0 drv_attr_store+0x21/0x50 sysfs_kf_write+0x4a/0x80 kernfs_fop_write_iter+0x169/0x220 vfs_write+0x293/0x560 ksys_write+0x72/0xf0 __x64_sys_write+0x19/0x30 x64_sys_call+0x2bf/0x2660 do_syscall_64+0x93/0xb60 entry_SYSCALL_64_after_hwframe+0x76/0x7e other info that might help us debug this: Chain exists of: (work_completion)(&(&devcd->del_wk)->work) --> kn->active#236 --> &devcd->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&devcd->mutex); lock(kn->active#236); lock(&devcd->mutex); lock((work_completion)(&(&devcd->del_wk)->work)); *** DEADLOCK *** 5 locks held by xe_fault_inject/5091: #0: ffff8881129f9488 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x72/0xf0 #1: ffff88810c755078 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x123/0x220 #2: ffff8881054811a0 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x55/0x280 #3: ffff888156815620 (&devcd->mutex){+.+.}-{3:3}, at: dev_coredump_put+0x3f/0xa0 #4: ffffffff8359e020 (rcu_read_lock){....}-{1:2}, at: __flush_work+0x72/0x660 stack backtrace: CPU: 14 UID: 0 PID: 5091 Comm: xe_fault_inject Tainted: G S U 6.16.0-rc6-lgci-xe-xe-pw-151626v3+ #1 PREEMPT_{RT,(lazy)} Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER Hardware name: Micro-Star International Co., Ltd. MS-7D25/PRO Z690-A DDR4(MS-7D25), BIOS 1.10 12/13/2021 Call Trace: <TASK> dump_stack_lvl+0x91/0xf0 dump_stack+0x10/0x20 print_circular_bug+0x285/0x360 check_noncircular+0x135/0x150 ? register_lock_class+0x48/0x4a0 __lock_acquire+0x1661/0x2860 lock_acquire+0xc4/0x2f0 ? __flush_work+0x25d/0x660 ? mark_held_locks+0x46/0x90 ? __flush_work+0x25d/0x660 __flush_work+0x27a/0x660 ? __flush_work+0x25d/0x660 ? trace_hardirqs_on+0x1e/0xd0 ? __pfx_wq_barrier_func+0x10/0x10 flush_delayed_work+0x5d/0xa0 dev_coredump_put+0x63/0xa0 xe_driver_devcoredump_fini+0x12/0x20 [xe] devm_action_release+0x12/0x30 release_nodes+0x3a/0x120 devres_release_all+0x8a/0xd0 device_unbind_cleanup+0x12/0x80 device_release_driver_internal+0x23a/0x280 ? bus_find_device+0xa8/0xe0 device_driver_detach+0x14/0x20 unbind_store+0xaf/0xc0 drv_attr_store+0x21/0x50 sysfs_kf_write+0x4a/0x80 kernfs_fop_write_iter+0x169/0x220 vfs_write+0x293/0x560 ksys_write+0x72/0xf0 __x64_sys_write+0x19/0x30 x64_sys_call+0x2bf/0x2660 do_syscall_64+0x93/0xb60 ? __f_unlock_pos+0x15/0x20 ? __x64_sys_getdents64+0x9b/0x130 ? __pfx_filldir64+0x10/0x10 ? do_syscall_64+0x1a2/0xb60 ? clear_bhb_loop+0x30/0x80 ? clear_bhb_loop+0x30/0x80 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x76e292edd574 Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 80 3d d5 ea 0e 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89 RSP: 002b:00007fffe247a828 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000076e292edd574 RDX: 000000000000000c RSI: 00006267f6306063 RDI: 000000000000000b RBP: 000000000000000c R08: 000076e292fc4b20 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00006267f6306063 R13: 000000000000000b R14: 00006267e6859c00 R15: 000076e29322a000 </TASK> xe 0000:03:00.0: [drm] Xe device coredump has been deleted. Fixes: 01daccf74832 ("devcoredump : Serialize devcd_del work") Cc: Mukesh Ojha <quic_mojha(a)quicinc.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: Johannes Berg <johannes(a)sipsolutions.net> Cc: Rafael J. Wysocki <rafael(a)kernel.org> Cc: Danilo Krummrich <dakr(a)kernel.org> Cc: linux-kernel(a)vger.kernel.org Cc: stable(a)vger.kernel.org # v6.1+ Signed-off-by: Maarten Lankhorst <dev(a)lankhorst.se> Cc: Matthew Brost <matthew.brost(a)intel.com> Acked-by: Mukesh Ojha <mukesh.ojha(a)oss.qualcomm.com> Link: https://lore.kernel.org/r/20250723142416.1020423-1-dev@lankhorst.se Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c index 37faf6156d7c..55bdc7f5e59d 100644 --- a/drivers/base/devcoredump.c +++ b/drivers/base/devcoredump.c @@ -23,50 +23,46 @@ struct devcd_entry { void *data; size_t datalen; /* - * Here, mutex is required to serialize the calls to del_wk work between - * user/kernel space which happens when devcd is added with device_add() - * and that sends uevent to user space. User space reads the uevents, - * and calls to devcd_data_write() which try to modify the work which is - * not even initialized/queued from devcoredump. + * There are 2 races for which mutex is required. * + * The first race is between device creation and userspace writing to + * schedule immediately destruction. * + * This race is handled by arming the timer before device creation, but + * when device creation fails the timer still exists. * - * cpu0(X) cpu1(Y) + * To solve this, hold the mutex during device_add(), and set + * init_completed on success before releasing the mutex. * - * dev_coredump() uevent sent to user space - * device_add() ======================> user space process Y reads the - * uevents writes to devcd fd - * which results into writes to + * That way the timer will never fire until device_add() is called, + * it will do nothing if init_completed is not set. The timer is also + * cancelled in that case. * - * devcd_data_write() - * mod_delayed_work() - * try_to_grab_pending() - * timer_delete() - * debug_assert_init() - * INIT_DELAYED_WORK() - * schedule_delayed_work() - * - * - * Also, mutex alone would not be enough to avoid scheduling of - * del_wk work after it get flush from a call to devcd_free() - * mentioned as below. - * - * disabled_store() - * devcd_free() - * mutex_lock() devcd_data_write() - * flush_delayed_work() - * mutex_unlock() - * mutex_lock() - * mod_delayed_work() - * mutex_unlock() - * So, delete_work flag is required. + * The second race involves multiple parallel invocations of devcd_free(), + * add a deleted flag so only 1 can call the destructor. */ struct mutex mutex; - bool delete_work; + bool init_completed, deleted; struct module *owner; ssize_t (*read)(char *buffer, loff_t offset, size_t count, void *data, size_t datalen); void (*free)(void *data); + /* + * If nothing interferes and device_add() was returns success, + * del_wk will destroy the device after the timer fires. + * + * Multiple userspace processes can interfere in the working of the timer: + * - Writing to the coredump will reschedule the timer to run immediately, + * if still armed. + * + * This is handled by using "if (cancel_delayed_work()) { + * schedule_delayed_work() }", to prevent re-arming after having + * been previously fired. + * - Writing to /sys/class/devcoredump/disabled will destroy the + * coredump synchronously. + * This is handled by using disable_delayed_work_sync(), and then + * checking if deleted flag is set with &devcd->mutex held. + */ struct delayed_work del_wk; struct device *failing_dev; }; @@ -95,14 +91,27 @@ static void devcd_dev_release(struct device *dev) kfree(devcd); } +static void __devcd_del(struct devcd_entry *devcd) +{ + devcd->deleted = true; + device_del(&devcd->devcd_dev); + put_device(&devcd->devcd_dev); +} + static void devcd_del(struct work_struct *wk) { struct devcd_entry *devcd; + bool init_completed; devcd = container_of(wk, struct devcd_entry, del_wk.work); - device_del(&devcd->devcd_dev); - put_device(&devcd->devcd_dev); + /* devcd->mutex serializes against dev_coredumpm_timeout */ + mutex_lock(&devcd->mutex); + init_completed = devcd->init_completed; + mutex_unlock(&devcd->mutex); + + if (init_completed) + __devcd_del(devcd); } static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj, @@ -122,12 +131,12 @@ static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj, struct device *dev = kobj_to_dev(kobj); struct devcd_entry *devcd = dev_to_devcd(dev); - mutex_lock(&devcd->mutex); - if (!devcd->delete_work) { - devcd->delete_work = true; - mod_delayed_work(system_wq, &devcd->del_wk, 0); - } - mutex_unlock(&devcd->mutex); + /* + * Although it's tempting to use mod_delayed work here, + * that will cause a reschedule if the timer already fired. + */ + if (cancel_delayed_work(&devcd->del_wk)) + schedule_delayed_work(&devcd->del_wk, 0); return count; } @@ -151,11 +160,21 @@ static int devcd_free(struct device *dev, void *data) { struct devcd_entry *devcd = dev_to_devcd(dev); + /* + * To prevent a race with devcd_data_write(), disable work and + * complete manually instead. + * + * We cannot rely on the return value of + * disable_delayed_work_sync() here, because it might be in the + * middle of a cancel_delayed_work + schedule_delayed_work pair. + * + * devcd->mutex here guards against multiple parallel invocations + * of devcd_free(). + */ + disable_delayed_work_sync(&devcd->del_wk); mutex_lock(&devcd->mutex); - if (!devcd->delete_work) - devcd->delete_work = true; - - flush_delayed_work(&devcd->del_wk); + if (!devcd->deleted) + __devcd_del(devcd); mutex_unlock(&devcd->mutex); return 0; } @@ -179,12 +198,10 @@ static ssize_t disabled_show(const struct class *class, const struct class_attri * put_device() <- last reference * error = fn(dev, data) devcd_dev_release() * devcd_free(dev, data) kfree(devcd) - * mutex_lock(&devcd->mutex); * * * In the above diagram, it looks like disabled_store() would be racing with parallelly - * running devcd_del() and result in memory abort while acquiring devcd->mutex which - * is called after kfree of devcd memory after dropping its last reference with + * running devcd_del() and result in memory abort after dropping its last reference with * put_device(). However, this will not happens as fn(dev, data) runs * with its own reference to device via klist_node so it is not its last reference. * so, above situation would not occur. @@ -374,7 +391,7 @@ void dev_coredumpm_timeout(struct device *dev, struct module *owner, devcd->read = read; devcd->free = free; devcd->failing_dev = get_device(dev); - devcd->delete_work = false; + devcd->deleted = false; mutex_init(&devcd->mutex); device_initialize(&devcd->devcd_dev); @@ -383,8 +400,14 @@ void dev_coredumpm_timeout(struct device *dev, struct module *owner, atomic_inc_return(&devcd_count)); devcd->devcd_dev.class = &devcd_class; - mutex_lock(&devcd->mutex); dev_set_uevent_suppress(&devcd->devcd_dev, true); + + /* devcd->mutex prevents devcd_del() completing until init finishes */ + mutex_lock(&devcd->mutex); + devcd->init_completed = false; + INIT_DELAYED_WORK(&devcd->del_wk, devcd_del); + schedule_delayed_work(&devcd->del_wk, timeout); + if (device_add(&devcd->devcd_dev)) goto put_device; @@ -401,13 +424,20 @@ void dev_coredumpm_timeout(struct device *dev, struct module *owner, dev_set_uevent_suppress(&devcd->devcd_dev, false); kobject_uevent(&devcd->devcd_dev.kobj, KOBJ_ADD); - INIT_DELAYED_WORK(&devcd->del_wk, devcd_del); - schedule_delayed_work(&devcd->del_wk, timeout); + + /* + * Safe to run devcd_del() now that we are done with devcd_dev. + * Alternatively we could have taken a ref on devcd_dev before + * dropping the lock. + */ + devcd->init_completed = true; mutex_unlock(&devcd->mutex); return; put_device: - put_device(&devcd->devcd_dev); mutex_unlock(&devcd->mutex); + cancel_delayed_work_sync(&devcd->del_wk); + put_device(&devcd->devcd_dev); + put_module: module_put(owner); free:

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FAILED: patch "[PATCH] can: gs_usb: increase max interface to U8_MAX" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 2a27f6a8fb5722223d526843040f747e9b0e8060 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025102041-mounting-pursuit-e9d3@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 2a27f6a8fb5722223d526843040f747e9b0e8060 Mon Sep 17 00:00:00 2001 From: Celeste Liu <uwu(a)coelacanthus.name> Date: Tue, 30 Sep 2025 19:34:28 +0800 Subject: [PATCH] can: gs_usb: increase max interface to U8_MAX This issue was found by Runcheng Lu when develop HSCanT USB to CAN FD converter[1]. The original developers may have only 3 interfaces device to test so they write 3 here and wait for future change. During the HSCanT development, we actually used 4 interfaces, so the limitation of 3 is not enough now. But just increase one is not future-proofed. Since the channel index type in gs_host_frame is u8, just make canch[] become a flexible array with a u8 index, so it naturally constraint by U8_MAX and avoid statically allocate 256 pointer for every gs_usb device. [1]: https://github.com/cherry-embedded/HSCanT-hardware Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices") Reported-by: Runcheng Lu <runcheng.lu(a)hpmicro.com> Cc: stable(a)vger.kernel.org Reviewed-by: Vincent Mailhol <mailhol(a)kernel.org> Signed-off-by: Celeste Liu <uwu(a)coelacanthus.name> Link: https://patch.msgid.link/20250930-gs-usb-max-if-v5-1-863330bf6666@coelacant… Signed-off-by: Marc Kleine-Budde <mkl(a)pengutronix.de> diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c index c9482d6e947b..9fb4cbbd6d6d 100644 --- a/drivers/net/can/usb/gs_usb.c +++ b/drivers/net/can/usb/gs_usb.c @@ -289,11 +289,6 @@ struct gs_host_frame { #define GS_MAX_RX_URBS 30 #define GS_NAPI_WEIGHT 32 -/* Maximum number of interfaces the driver supports per device. - * Current hardware only supports 3 interfaces. The future may vary. - */ -#define GS_MAX_INTF 3 - struct gs_tx_context { struct gs_can *dev; unsigned int echo_id; @@ -324,7 +319,6 @@ struct gs_can { /* usb interface struct */ struct gs_usb { - struct gs_can *canch[GS_MAX_INTF]; struct usb_anchor rx_submitted; struct usb_device *udev; @@ -336,9 +330,11 @@ struct gs_usb { unsigned int hf_size_rx; u8 active_channels; + u8 channel_cnt; unsigned int pipe_in; unsigned int pipe_out; + struct gs_can *canch[] __counted_by(channel_cnt); }; /* 'allocate' a tx context. @@ -599,7 +595,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) } /* device reports out of range channel id */ - if (hf->channel >= GS_MAX_INTF) + if (hf->channel >= parent->channel_cnt) goto device_detach; dev = parent->canch[hf->channel]; @@ -699,7 +695,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb) /* USB failure take down all interfaces */ if (rc == -ENODEV) { device_detach: - for (rc = 0; rc < GS_MAX_INTF; rc++) { + for (rc = 0; rc < parent->channel_cnt; rc++) { if (parent->canch[rc]) netif_device_detach(parent->canch[rc]->netdev); } @@ -1460,17 +1456,19 @@ static int gs_usb_probe(struct usb_interface *intf, icount = dconf.icount + 1; dev_info(&intf->dev, "Configuring for %u interfaces\n", icount); - if (icount > GS_MAX_INTF) { + if (icount > type_max(parent->channel_cnt)) { dev_err(&intf->dev, "Driver cannot handle more that %u CAN interfaces\n", - GS_MAX_INTF); + type_max(parent->channel_cnt)); return -EINVAL; } - parent = kzalloc(sizeof(*parent), GFP_KERNEL); + parent = kzalloc(struct_size(parent, canch, icount), GFP_KERNEL); if (!parent) return -ENOMEM; + parent->channel_cnt = icount; + init_usb_anchor(&parent->rx_submitted); usb_set_intfdata(intf, parent); @@ -1531,7 +1529,7 @@ static void gs_usb_disconnect(struct usb_interface *intf) return; } - for (i = 0; i < GS_MAX_INTF; i++) + for (i = 0; i < parent->channel_cnt; i++) if (parent->canch[i]) gs_destroy_candev(parent->canch[i]);

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