February 2025 - Linux-stable-mirror

[PATCH v3 0/2] Allow non-coherent video capture buffers on Rockchip ISP V1

by Mikhail Rudenko

This small series adds support for non-coherent video capture buffers on Rockchip ISP V1. Patch 1 fixes cache management for dmabuf's allocated by dma-contig allocator. Patch 2 allows non-coherent allocations on the rkisp1 capture queue. Some timing measurements are provided in the commit message of patch 2. Signed-off-by: Mikhail Rudenko <mike.rudenko(a)gmail.com> --- Changes in v3: - ignore skip_cache_sync_* flags in vb2_dc_dmabuf_ops_{begin,end}_cpu_access - invalidate/flush kernel mappings as appropriate if they exist - use dma_sync_sgtable_* instead of dma_sync_sg_* - Link to v2: https://lore.kernel.org/r/20250115-b4-rkisp-noncoherent-v2-0-0853e1a24012@g… Changes in v2: - Fix vb2_dc_dmabuf_ops_{begin,end}_cpu_access() for non-coherent buffers. - Add cache management timing information to patch 2 commit message. - Link to v1: https://lore.kernel.org/r/20250102-b4-rkisp-noncoherent-v1-1-bba164f7132c@g… --- Mikhail Rudenko (2): media: videobuf2: Fix dmabuf cache sync/flush in dma-contig media: rkisp1: Allow non-coherent video capture buffers .../media/common/videobuf2/videobuf2-dma-contig.c | 22 ++++++++++++++++++++++ .../platform/rockchip/rkisp1/rkisp1-capture.c | 1 + 2 files changed, 23 insertions(+) --- base-commit: c4b7779abc6633677e6edb79e2809f4f61fde157 change-id: 20241231-b4-rkisp-noncoherent-ad6e7c7a68ba Best regards, -- Mikhail Rudenko <mike.rudenko(a)gmail.com>

3 months, 2 weeks

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RE: Supercharge your lead generation

by Sophia Martinez

Hi there, I'm reaching out to see if you have any updates regarding my previous email. I look forward to your thoughts. Regards, Sophia ________________________________ From: Sophia Martinez Sent: 25 February 2025 02:32 To: linux-stable-mirror(a)lists.linaro.org<mailto:linux-stable-mirror@lists.linaro.org> Subject: Supercharge your lead generation Hi there, I hope you're doing good. Would you be interested in Xero users Database? Please let me know your interest so that I'll get back with count and pricing for your review. I will be looking forward for your response on this. Best Regards, Sophia Martinez Demand Generation Specialist To stop receiving emails, respond with Leave out.

3 months, 2 weeks

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[PATCH v3 1/2] vmlinux.lds: Ensure that const vars with relocations are mapped R/O

by Ard Biesheuvel

From: Ard Biesheuvel <ardb(a)kernel.org> In the kernel, there are architectures (x86, arm64) that perform boot-time relocation (for KASLR) without relying on PIE codegen. In this case, all const global objects are emitted into .rodata, including const objects with fields that will be fixed up by the boot-time relocation code. This implies that .rodata (and .text in some cases) need to be writable at boot, but they will usually be mapped read-only as soon as the boot completes. When using PIE codegen, the compiler will emit const global objects into .data.rel.ro rather than .rodata if the object contains fields that need such fixups at boot-time. This permits the linker to annotate such regions as requiring read-write access only at load time, but not at execution time (in user space), while keeping .rodata truly const (in user space, this is important for reducing the CoW footprint of dynamic executables). This distinction does not matter for the kernel, but it does imply that const data will end up in writable memory if the .data.rel.ro sections are not treated in a special way, as they will end up in the writable .data segment by default. So emit .data.rel.ro into the .rodata segment. Cc: <stable(a)vger.kernel.org> Signed-off-by: Ard Biesheuvel <ardb(a)kernel.org> --- include/asm-generic/vmlinux.lds.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 02a4adb4a999..0d5b186abee8 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -457,7 +457,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG) . = ALIGN((align)); \ .rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \ __start_rodata = .; \ - *(.rodata) *(.rodata.*) \ + *(.rodata) *(.rodata.*) *(.data.rel.ro*) \ SCHED_DATA \ RO_AFTER_INIT_DATA /* Read only after init */ \ . = ALIGN(8); \ -- 2.48.1.601.g30ceb7b040-goog

3 months, 2 weeks

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[PATCH 3/3] drm/xe/userptr: Unmap userptrs in the mmu notifier

by Thomas Hellström

If userptr pages are freed after a call to the xe mmu notifier, the device will not be blocked out from theoretically accessing these pages unless they are also unmapped from the iommu, and this violates some aspects of the iommu-imposed security. Ensure that userptrs are unmapped in the mmu notifier to mitigate this. A naive attempt would try to free the sg table, but the sg table itself may be accessed by a concurrent bind operation, so settle for unly unmapping. Fixes: 81e058a3e7fd ("drm/xe: Introduce helper to populate userptr") Cc: Oak Zeng <oak.zeng(a)intel.com> Cc: <stable(a)vger.kernel.org> # v6.10+ Signed-off-by: Thomas Hellström <thomas.hellstrom(a)linux.intel.com> --- drivers/gpu/drm/xe/xe_hmm.c | 49 ++++++++++++++++++++++++++------ drivers/gpu/drm/xe/xe_hmm.h | 2 ++ drivers/gpu/drm/xe/xe_vm.c | 4 +++ drivers/gpu/drm/xe/xe_vm_types.h | 4 +++ 4 files changed, 50 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_hmm.c b/drivers/gpu/drm/xe/xe_hmm.c index d3b5551496d0..35d257d4680f 100644 --- a/drivers/gpu/drm/xe/xe_hmm.c +++ b/drivers/gpu/drm/xe/xe_hmm.c @@ -136,6 +136,43 @@ static int xe_build_sg(struct xe_device *xe, struct hmm_range *range, DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_KERNEL_MAPPING); } +static void xe_hmm_userptr_set_mapped(struct xe_userptr_vma *uvma) +{ + struct xe_userptr *userptr = &uvma->userptr; + struct xe_vm *vm = xe_vma_vm(&uvma->vma); + + lockdep_assert_held_write(&vm->lock); + + mutex_lock(&userptr->unmap_mutex); + xe_assert(vm->xe, !userptr->mapped); + userptr->mapped = true; + mutex_unlock(&userptr->unmap_mutex); +} + +void xe_hmm_userptr_unmap(struct xe_userptr_vma *uvma) +{ + struct xe_userptr *userptr = &uvma->userptr; + struct xe_vma *vma = &uvma->vma; + bool write = !xe_vma_read_only(vma); + struct xe_vm *vm = xe_vma_vm(vma); + struct xe_device *xe = vm->xe; + + if (!lockdep_is_held_type(&vm->userptr.notifier_lock, 0) && + !lockdep_is_held_type(&vm->lock, 0) && + !(vma->gpuva.flags & XE_VMA_DESTROYED)) { + xe_vm_assert_held(vm); + lockdep_assert_held(&vm->userptr.notifier_lock); + lockdep_assert_held(&vm->lock); + } + + mutex_lock(&userptr->unmap_mutex); + if (userptr->sg && userptr->mapped) + dma_unmap_sgtable(xe->drm.dev, userptr->sg, + write ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE, 0); + userptr->mapped = false; + mutex_unlock(&userptr->unmap_mutex); +} + /** * xe_hmm_userptr_free_sg() - Free the scatter gather table of userptr * @uvma: the userptr vma which hold the scatter gather table @@ -147,16 +184,9 @@ static int xe_build_sg(struct xe_device *xe, struct hmm_range *range, void xe_hmm_userptr_free_sg(struct xe_userptr_vma *uvma) { struct xe_userptr *userptr = &uvma->userptr; - struct xe_vma *vma = &uvma->vma; - bool write = !xe_vma_read_only(vma); - struct xe_vm *vm = xe_vma_vm(vma); - struct xe_device *xe = vm->xe; - struct device *dev = xe->drm.dev; - - xe_assert(xe, userptr->sg); - dma_unmap_sgtable(dev, userptr->sg, - write ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE, 0); + xe_assert(xe_vma_vm(&uvma->vma)->xe, userptr->sg); + xe_hmm_userptr_unmap(uvma); sg_free_table(userptr->sg); userptr->sg = NULL; } @@ -290,6 +320,7 @@ int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma, xe_mark_range_accessed(&hmm_range, write); userptr->sg = &userptr->sgt; + xe_hmm_userptr_set_mapped(uvma); userptr->notifier_seq = hmm_range.notifier_seq; up_read(&vm->userptr.notifier_lock); kvfree(pfns); diff --git a/drivers/gpu/drm/xe/xe_hmm.h b/drivers/gpu/drm/xe/xe_hmm.h index 9602cb7d976d..0ea98d8e7bbc 100644 --- a/drivers/gpu/drm/xe/xe_hmm.h +++ b/drivers/gpu/drm/xe/xe_hmm.h @@ -13,4 +13,6 @@ struct xe_userptr_vma; int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma, bool is_mm_mmap_locked); void xe_hmm_userptr_free_sg(struct xe_userptr_vma *uvma); + +void xe_hmm_userptr_unmap(struct xe_userptr_vma *uvma); #endif diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c index dd422ac95dc0..3dbd3d38008a 100644 --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -621,6 +621,8 @@ static void __vma_userptr_invalidate(struct xe_vm *vm, struct xe_userptr_vma *uv err = xe_vm_invalidate_vma(vma); XE_WARN_ON(err); } + + xe_hmm_userptr_unmap(uvma); } static bool vma_userptr_invalidate(struct mmu_interval_notifier *mni, @@ -1039,6 +1041,7 @@ static struct xe_vma *xe_vma_create(struct xe_vm *vm, INIT_LIST_HEAD(&userptr->invalidate_link); INIT_LIST_HEAD(&userptr->repin_link); vma->gpuva.gem.offset = bo_offset_or_userptr; + mutex_init(&userptr->unmap_mutex); err = mmu_interval_notifier_insert(&userptr->notifier, current->mm, @@ -1080,6 +1083,7 @@ static void xe_vma_destroy_late(struct xe_vma *vma) * them anymore */ mmu_interval_notifier_remove(&userptr->notifier); + mutex_destroy(&userptr->unmap_mutex); xe_vm_put(vm); } else if (xe_vma_is_null(vma)) { xe_vm_put(vm); diff --git a/drivers/gpu/drm/xe/xe_vm_types.h b/drivers/gpu/drm/xe/xe_vm_types.h index 1fe79bf23b6b..eca73c4197d4 100644 --- a/drivers/gpu/drm/xe/xe_vm_types.h +++ b/drivers/gpu/drm/xe/xe_vm_types.h @@ -59,12 +59,16 @@ struct xe_userptr { struct sg_table *sg; /** @notifier_seq: notifier sequence number */ unsigned long notifier_seq; + /** @unmap_mutex: Mutex protecting dma-unmapping */ + struct mutex unmap_mutex; /** * @initial_bind: user pointer has been bound at least once. * write: vm->userptr.notifier_lock in read mode and vm->resv held. * read: vm->userptr.notifier_lock in write mode or vm->resv held. */ bool initial_bind; + /** @mapped: Whether the @sgt sg-table is dma-mapped. Protected by @unmap_mutex. */ + bool mapped; #if IS_ENABLED(CONFIG_DRM_XE_USERPTR_INVAL_INJECT) u32 divisor; #endif -- 2.48.1

3 months, 2 weeks

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Visitor's Contact List Of Embedded World Exhibition 2025!

by Michelle Stone

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3 months, 2 weeks

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[PATCH] hfsplus: fix 32-bit integer overflow in statfs()

by Mikael Heino

Very large volumes (20TB) would cause an integer overflow in statfs() and display incorrect block counts. Statfs structure's f_blocks, f_bfree and f_bavail are stored as a u64, but the promotion to 64-bit happens after the shift has been done. Fix this issue by promoting the value before shifting. The problem can be reproduced by creating a 20TB volume for HFS+, mounting and running statfs() on the mounted volume. Cc: stable(a)vger.kernel.org Cc: linux-fsdevel(a)vger.kernel.org Reviewed-by: Anton Altaparmakov <anton(a)tuxera.com> Signed-off-by: Mikael Heino <mikael(a)tuxera.com> --- fs/hfsplus/super.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c index 948b8aaee33e..00bb23b0ff7d 100644 --- a/fs/hfsplus/super.c +++ b/fs/hfsplus/super.c @@ -322,8 +322,8 @@ static int hfsplus_statfs(struct dentry *dentry, struct kstatfs *buf) buf->f_type = HFSPLUS_SUPER_MAGIC; buf->f_bsize = sb->s_blocksize; - buf->f_blocks = sbi->total_blocks << sbi->fs_shift; - buf->f_bfree = sbi->free_blocks << sbi->fs_shift; + buf->f_blocks = (u64)sbi->total_blocks << sbi->fs_shift; + buf->f_bfree = (u64)sbi->free_blocks << sbi->fs_shift; buf->f_bavail = buf->f_bfree; buf->f_files = 0xFFFFFFFF; buf->f_ffree = 0xFFFFFFFF - sbi->next_cnid; -- 2.25.1

3 months, 2 weeks

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[PATCH 5.10/5.15] team: prevent adding a device which is already a team device lower

by Alexey Panov

From: Octavian Purdila <tavip(a)google.com> commit 3fff5da4ca2164bb4d0f1e6cd33f6eb8a0e73e50 upstream. Prevent adding a device which is already a team device lower, e.g. adding veth0 if vlan1 was already added and veth0 is a lower of vlan1. This is not useful in practice and can lead to recursive locking: $ ip link add veth0 type veth peer name veth1 $ ip link set veth0 up $ ip link set veth1 up $ ip link add link veth0 name veth0.1 type vlan protocol 802.1Q id 1 $ ip link add team0 type team $ ip link set veth0.1 down $ ip link set veth0.1 master team0 team0: Port device veth0.1 added $ ip link set veth0 down $ ip link set veth0 master team0 ============================================ WARNING: possible recursive locking detected 6.13.0-rc2-virtme-00441-ga14a429069bb #46 Not tainted -------------------------------------------- ip/7684 is trying to acquire lock: ffff888016848e00 (team->team_lock_key){+.+.}-{4:4}, at: team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) but task is already holding lock: ffff888016848e00 (team->team_lock_key){+.+.}-{4:4}, at: team_add_slave (drivers/net/team/team_core.c:1147 drivers/net/team/team_core.c:1977) other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(team->team_lock_key); lock(team->team_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by ip/7684: stack backtrace: CPU: 3 UID: 0 PID: 7684 Comm: ip Not tainted 6.13.0-rc2-virtme-00441-ga14a429069bb #46 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:122) print_deadlock_bug.cold (kernel/locking/lockdep.c:3040) __lock_acquire (kernel/locking/lockdep.c:3893 kernel/locking/lockdep.c:5226) ? netlink_broadcast_filtered (net/netlink/af_netlink.c:1548) lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 2)) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? lock_acquire (kernel/locking/lockdep.c:5822) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) __mutex_lock (kernel/locking/mutex.c:587 kernel/locking/mutex.c:735) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) ? fib_sync_up (net/ipv4/fib_semantics.c:2167) ? team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) team_device_event (drivers/net/team/team_core.c:2928 drivers/net/team/team_core.c:2951 drivers/net/team/team_core.c:2973) notifier_call_chain (kernel/notifier.c:85) call_netdevice_notifiers_info (net/core/dev.c:1996) __dev_notify_flags (net/core/dev.c:8993) ? __dev_change_flags (net/core/dev.c:8975) dev_change_flags (net/core/dev.c:9027) vlan_device_event (net/8021q/vlan.c:85 net/8021q/vlan.c:470) ? br_device_event (net/bridge/br.c:143) notifier_call_chain (kernel/notifier.c:85) call_netdevice_notifiers_info (net/core/dev.c:1996) dev_open (net/core/dev.c:1519 net/core/dev.c:1505) team_add_slave (drivers/net/team/team_core.c:1219 drivers/net/team/team_core.c:1977) ? __pfx_team_add_slave (drivers/net/team/team_core.c:1972) do_set_master (net/core/rtnetlink.c:2917) do_setlink.isra.0 (net/core/rtnetlink.c:3117) Reported-by: syzbot+3c47b5843403a45aef57(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3c47b5843403a45aef57 Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device") Signed-off-by: Octavian Purdila <tavip(a)google.com> Reviewed-by: Hangbin Liu <liuhangbin(a)gmail.com> Signed-off-by: David S. Miller <davem(a)davemloft.net> [Alexey: fixed path from team_core.c to team.c to resolve merge conflict] Signed-off-by: Alexey Panov <apanov(a)astralinux.ru> --- drivers/net/team/team.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index 5e5af71a85ac..015151cd2222 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -1166,6 +1166,13 @@ static int team_port_add(struct team *team, struct net_device *port_dev, return -EBUSY; } + if (netdev_has_upper_dev(port_dev, dev)) { + NL_SET_ERR_MSG(extack, "Device is already a lower device of the team interface"); + netdev_err(dev, "Device %s is already a lower device of the team interface\n", + portname); + return -EBUSY; + } + if (port_dev->features & NETIF_F_VLAN_CHALLENGED && vlan_uses_dev(dev)) { NL_SET_ERR_MSG(extack, "Device is VLAN challenged and team device has VLAN set up"); -- 2.30.2

3 months, 2 weeks

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[PATCH] xhci: Restrict USB4 tunnel detection for USB3 devices to Intel hosts

by Marc Zyngier

When adding support for USB3-over-USB4 tunnelling detection, a check for an Intel-specific capability was added. This capability, which goes by ID 206, is used without any check that we are actually dealing with an Intel host. As it turns out, the Cadence XHCI controller *also* exposes an extended capability numbered 206 (for unknown purposes), but of course doesn't have the Intel-specific registers that the tunnelling code is trying to access. Fun follows. The core of the problems is that the tunnelling code blindly uses vendor-specific capabilities without any check (the Intel-provided documentation I have at hand indicates that 192-255 are indeed vendor-specific). Restrict the detection code to Intel HW for real, preventing any further explosion on my (non-Intel) HW. Cc: Mathias Nyman <mathias.nyman(a)linux.intel.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: stable(a)vger.kernel.org Fixes: 948ce83fbb7df ("xhci: Add USB4 tunnel detection for USB3 devices on Intel hosts") Signed-off-by: Marc Zyngier <maz(a)kernel.org> --- drivers/usb/host/xhci-hub.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c index 9693464c05204..69c278b64084b 100644 --- a/drivers/usb/host/xhci-hub.c +++ b/drivers/usb/host/xhci-hub.c @@ -12,6 +12,7 @@ #include <linux/slab.h> #include <linux/unaligned.h> #include <linux/bitfield.h> +#include <linux/pci.h> #include "xhci.h" #include "xhci-trace.h" @@ -770,9 +771,16 @@ static int xhci_exit_test_mode(struct xhci_hcd *xhci) enum usb_link_tunnel_mode xhci_port_is_tunneled(struct xhci_hcd *xhci, struct xhci_port *port) { + struct usb_hcd *hcd; void __iomem *base; u32 offset; + /* Don't try and probe this capability for non-Intel hosts */ + hcd = xhci_to_hcd(xhci); + if (!dev_is_pci(hcd->self.controller) || + to_pci_dev(hcd->self.controller)->vendor != PCI_VENDOR_ID_INTEL) + return USB_LINK_UNKNOWN; + base = &xhci->cap_regs->hc_capbase; offset = xhci_find_next_ext_cap(base, 0, XHCI_EXT_CAPS_INTEL_SPR_SHADOW); -- 2.39.2

3 months, 2 weeks

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[PATCH v3] mfd: ene-kb3930: Fix a potential NULL pointer dereference

by Chenyuan Yang

The off_gpios could be NULL. Add missing check in the kb3930_probe(). This is similar to the issue fixed in commit b1ba8bcb2d1f ("backlight: hx8357: Fix potential NULL pointer dereference"). This was detected by our static analysis tool. Fixes: ede6b2d1dfc0 ("mfd: ene-kb3930: Add driver for ENE KB3930 Embedded Controller") Signed-off-by: Chenyuan Yang <chenyuan0y(a)gmail.com> Suggested-by: Lee Jones <lee(a)kernel.org> Cc: stable(a)vger.kernel.org --- drivers/mfd/ene-kb3930.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mfd/ene-kb3930.c b/drivers/mfd/ene-kb3930.c index fa0ad2f14a39..9460a67acb0b 100644 --- a/drivers/mfd/ene-kb3930.c +++ b/drivers/mfd/ene-kb3930.c @@ -162,7 +162,7 @@ static int kb3930_probe(struct i2c_client *client) devm_gpiod_get_array_optional(dev, "off", GPIOD_IN); if (IS_ERR(ddata->off_gpios)) return PTR_ERR(ddata->off_gpios); - if (ddata->off_gpios->ndescs < 2) { + if (ddata->off_gpios && ddata->off_gpios->ndescs < 2) { dev_err(dev, "invalid off-gpios property\n"); return -EINVAL; } -- 2.34.1

3 months, 2 weeks

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[PATCH RESEND v2] Documentation/no_hz: Remove description that states boot CPU cannot be nohz_full

by Krishanth Jagaduri

From: Oleg Nesterov <oleg(a)redhat.com> sched/isolation: Prevent boot crash when the boot CPU is nohz_full [ Upstream commit 5097cbcb38e6e0d2627c9dde1985e91d2c9f880e ] Documentation/timers/no_hz.rst states that the "nohz_full=" mask must not include the boot CPU, which is no longer true after: commit 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full"). However after: aae17ebb53cd ("workqueue: Avoid using isolated cpus' timers on queue_delayed_work") the kernel will crash at boot time in this case; housekeeping_any_cpu() returns an invalid CPU number until smp_init() brings the first housekeeping CPU up. Change housekeeping_any_cpu() to check the result of cpumask_any_and() and return smp_processor_id() in this case. This is just the simple and backportable workaround which fixes the symptom, but smp_processor_id() at boot time should be safe at least for type == HK_TYPE_TIMER, this more or less matches the tick_do_timer_boot_cpu logic. There is no worry about cpu_down(); tick_nohz_cpu_down() will not allow to offline tick_do_timer_cpu (the 1st online housekeeping CPU). [ Apply only documentation changes as commit which causes boot crash when boot CPU is nohz_full is not backported to stable kernels - Krishanth ] Fixes: aae17ebb53cd ("workqueue: Avoid using isolated cpus' timers on queue_delayed_work") Reported-by: Chris von Recklinghausen <crecklin(a)redhat.com> Signed-off-by: Oleg Nesterov <oleg(a)redhat.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Reviewed-by: Phil Auld <pauld(a)redhat.com> Acked-by: Frederic Weisbecker <frederic(a)kernel.org> Link: https://lore.kernel.org/r/20240411143905.GA19288@redhat.com Closes: https://lore.kernel.org/all/20240402105847.GA24832@redhat.com/ Cc: stable(a)vger.kernel.org # 5.4+ Signed-off-by: Krishanth Jagaduri <Krishanth.Jagaduri(a)sony.com> --- Hi, Before kernel 6.9, Documentation/timers/no_hz.rst states that "nohz_full=" mask must not include the boot CPU, which is no longer true after commit 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full"). When trying LTS kernels between 5.4 and 6.6, we noticed we could use boot CPU as nohz_full but the information in the document was misleading. This was fixed upstream by commit 5097cbcb38e6 ("sched/isolation: Prevent boot crash when the boot CPU is nohz_full"). While it fixes the document description, it also fixes issue introduced by another commit aae17ebb53cd ("workqueue: Avoid using isolated cpus' timers on queue_delayed_work"). It is unlikely that upstream commit as a whole will be backported to stable kernels which does not contain the commit that introduced the issue of boot crash when boot CPU is nohz_full. Could we fix only the document portion in stable kernels 5.4+ that mentions boot CPU cannot be nohz_full? --- Changes in v2: - Add original changelog and trailers to commit message. - Add backport note for why only document portion is modified. - Link to v1: https://lore.kernel.org/r/20250205-send-oss-20250129-v1-1-d404921e6d7e@sony… --- Documentation/timers/no_hz.rst | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/Documentation/timers/no_hz.rst b/Documentation/timers/no_hz.rst index 065db217cb04fc252bbf6a05991296e7f1d3a4c5..16bda468423e88090c0dc467ca7a5c7f3fd2bf02 100644 --- a/Documentation/timers/no_hz.rst +++ b/Documentation/timers/no_hz.rst @@ -129,11 +129,8 @@ adaptive-tick CPUs: At least one non-adaptive-tick CPU must remain online to handle timekeeping tasks in order to ensure that system calls like gettimeofday() returns accurate values on adaptive-tick CPUs. (This is not an issue for CONFIG_NO_HZ_IDLE=y because there are no running -user processes to observe slight drifts in clock rate.) Therefore, the -boot CPU is prohibited from entering adaptive-ticks mode. Specifying a -"nohz_full=" mask that includes the boot CPU will result in a boot-time -error message, and the boot CPU will be removed from the mask. Note that -this means that your system must have at least two CPUs in order for +user processes to observe slight drifts in clock rate.) Note that this +means that your system must have at least two CPUs in order for CONFIG_NO_HZ_FULL=y to do anything for you. Finally, adaptive-ticks CPUs must have their RCU callbacks offloaded. --- base-commit: 219d54332a09e8d8741c1e1982f5eae56099de85 change-id: 20250129-send-oss-20250129-3c42dcf463eb Best regards, -- Krishanth Jagaduri <Krishanth.Jagaduri(a)sony.com>

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Linux-stable-mirror February 2025