The traversing of io_range_list with list_for_each_entry_rcu() is not properly protected by rcu_read_lock() and rcu_read_unlock(), so add them.

These functions mark the critical section scope where the list is protected for the reader, it cannot be "reclaimed". Any updater - in this case, the logical PIO registration functions - cannot update the list until the reader exits this critical section.

In addition, the list traversing used in logic_pio_register_range() does not need to use the rcu variant.

This is because we are already using io_range_mutex to guarantee mutual exclusion from mutating the list.

Cc: stable@vger.kernel.org Fixes: 031e3601869c ("lib: Add generic PIO mapping method") Signed-off-by: John Garry john.garry@huawei.com --- lib/logic_pio.c | 49 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 35 insertions(+), 14 deletions(-)

diff --git a/lib/logic_pio.c b/lib/logic_pio.c index feea48fd1a0d..761296376fbc 100644 --- a/lib/logic_pio.c +++ b/lib/logic_pio.c @@ -46,7 +46,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range) end = new_range->hw_start + new_range->size;

mutex_lock(&io_range_mutex); - list_for_each_entry_rcu(range, &io_range_list, list) { + list_for_each_entry(range, &io_range_list, list) { if (range->fwnode == new_range->fwnode) { /* range already there */ goto end_register; @@ -108,26 +108,38 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range) */ struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode) { - struct logic_pio_hwaddr *range; + struct logic_pio_hwaddr *range, *found_range = NULL;

+ rcu_read_lock(); list_for_each_entry_rcu(range, &io_range_list, list) { - if (range->fwnode == fwnode) - return range; + if (range->fwnode == fwnode) { + found_range = range; + break; + } } - return NULL; + rcu_read_unlock(); + + return found_range; }

/* Return a registered range given an input PIO token */ static struct logic_pio_hwaddr *find_io_range(unsigned long pio) { - struct logic_pio_hwaddr *range; + struct logic_pio_hwaddr *range, *found_range = NULL;

+ rcu_read_lock(); list_for_each_entry_rcu(range, &io_range_list, list) { - if (in_range(pio, range->io_start, range->size)) - return range; + if (in_range(pio, range->io_start, range->size)) { + found_range = range; + break; + } } - pr_err("PIO entry token %lx invalid\n", pio); - return NULL; + rcu_read_unlock(); + + if (!found_range) + pr_err("PIO entry token 0x%lx invalid\n", pio); + + return found_range; }

/** @@ -180,14 +192,23 @@ unsigned long logic_pio_trans_cpuaddr(resource_size_t addr) { struct logic_pio_hwaddr *range;

+ rcu_read_lock(); list_for_each_entry_rcu(range, &io_range_list, list) { if (range->flags != LOGIC_PIO_CPU_MMIO) continue; - if (in_range(addr, range->hw_start, range->size)) - return addr - range->hw_start + range->io_start; + if (in_range(addr, range->hw_start, range->size)) { + unsigned long cpuaddr; + + cpuaddr = addr - range->hw_start + range->io_start; + + rcu_read_unlock(); + return cpuaddr; + } } - pr_err("addr %llx not registered in io_range_list\n", - (unsigned long long) addr); + rcu_read_unlock(); + + pr_err("addr %pa not registered in io_range_list\n", &addr); + return ~0UL; }

Add a function to unregister a logical PIO range.

Logical PIO space can still be leaked when unregistering certain LOGIC_PIO_CPU_MMIO regions, but this acceptable for now since there are no callers to unregister LOGIC_PIO_CPU_MMIO regions, and the logical PIO region allocation scheme would need significant work to improve this.

Cc: stable@vger.kernel.org Signed-off-by: John Garry john.garry@huawei.com --- include/linux/logic_pio.h | 1 + lib/logic_pio.c | 14 ++++++++++++++ 2 files changed, 15 insertions(+)

diff --git a/include/linux/logic_pio.h b/include/linux/logic_pio.h index cbd9d8495690..88e1e6304a71 100644 --- a/include/linux/logic_pio.h +++ b/include/linux/logic_pio.h @@ -117,6 +117,7 @@ struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode); unsigned long logic_pio_trans_hwaddr(struct fwnode_handle *fwnode, resource_size_t hw_addr, resource_size_t size); int logic_pio_register_range(struct logic_pio_hwaddr *newrange); +void logic_pio_unregister_range(struct logic_pio_hwaddr *range); resource_size_t logic_pio_to_hwaddr(unsigned long pio); unsigned long logic_pio_trans_cpuaddr(resource_size_t hw_addr);

diff --git a/lib/logic_pio.c b/lib/logic_pio.c index d0165c88f705..905027574e5d 100644 --- a/lib/logic_pio.c +++ b/lib/logic_pio.c @@ -98,6 +98,20 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range) return ret; }

+/** + * logic_pio_unregister_range - unregister a logical PIO range for a host + * @range: pointer to the IO range which has been already registered. + * + * Unregister a previously-registered IO range node. + */ +void logic_pio_unregister_range(struct logic_pio_hwaddr *range) +{ + mutex_lock(&io_range_mutex); + list_del_rcu(&range->list); + mutex_unlock(&io_range_mutex); + synchronize_rcu(); +} + /** * find_io_range_by_fwnode - find logical PIO range for given FW node * @fwnode: FW node handle associated with logical PIO range

The original driver author seemed to be under the impression that a driver cannot be removed if it does not have a .remove method. Or maybe if it is a built-in platform driver.

This is not true. This crash can be created:

root@ubuntu:/sys/bus/platform/drivers/hisi-lpc# echo HISI0191:00 > unbind root@ubuntu:/sys/bus/platform/drivers/hisi-lpc# ipmitool raw 6 1 Unable to handle kernel paging request at virtual address ffff000010035010 Mem abort info: ESR = 0x96000047 Exception class = DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000047 CM = 0, WnR = 1 swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000000118b000 [ffff000010035010] pgd=0000041ffbfff003, pud=0000041ffbffe003, pmd=0000041ffbffd003, pte=0000000000000000 Internal error: Oops: 96000047 [#1] PREEMPT SMP Modules linked in: CPU: 17 PID: 1473 Comm: ipmitool Not tainted 5.2.0-rc5-00003-gf68c53b414a3-dirty #198 Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon D05 IT21 Nemo 2.0 RC0 04/18/2018 pstate: 20000085 (nzCv daIf -PAN -UAO) pc : hisi_lpc_target_in+0x7c/0x120 lr : hisi_lpc_target_in+0x70/0x120 sp : ffff00001efe3930 x29: ffff00001efe3930 x28: ffff841f9f599200 x27: 0000000000000002 x26: 0000000000000000 x25: 0000000000000080 x24: 00000000000000e4 x23: 0000000000000000 x22: 0000000000000064 x21: ffff801fb667d280 x20: 0000000000000001 x19: ffff00001efe39ac x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff841febe60340 x7 : ffff801fb55c52e8 x6 : 0000000000000000 x5 : 0000000000ffc0e3 x4 : 0000000000000001 x3 : ffff801fb667d280 x2 : 0000000000000001 x1 : ffff000010035010 x0 : ffff000010035000 Call trace: hisi_lpc_target_in+0x7c/0x120 hisi_lpc_comm_in+0x88/0x98 logic_inb+0x5c/0xb8 port_inb+0x18/0x20 bt_event+0x38/0x808 smi_event_handler+0x4c/0x5a0 check_start_timer_thread.part.4+0x40/0x58 sender+0x78/0x88 smi_send.isra.6+0x94/0x108 i_ipmi_request+0x2c4/0x8f8 ipmi_request_settime+0x124/0x160 handle_send_req+0x19c/0x208 ipmi_ioctl+0x2c0/0x990 do_vfs_ioctl+0xb8/0x8f8 ksys_ioctl+0x80/0xb8 __arm64_sys_ioctl+0x1c/0x28 el0_svc_common.constprop.0+0x64/0x160 el0_svc_handler+0x28/0x78 el0_svc+0x8/0xc Code: 941d1511 aa0003f9 f94006a0 91004001 (b9000034) ---[ end trace aa842b86af7069e4 ]---

The problem here is that the host goes away but the associated logical PIO region remains registered, as do the children devices.

Fix by adding a .remove method to tidy-up by removing the child devices and unregistering the logical PIO region.

Cc: stable@vger.kernel.org Fixes: adf38bb0b595 ("HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings") Signed-off-by: John Garry john.garry@huawei.com --- drivers/bus/hisi_lpc.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/hisi_lpc.c b/drivers/bus/hisi_lpc.c index 6d301aafcad2..20c957185af2 100644 --- a/drivers/bus/hisi_lpc.c +++ b/drivers/bus/hisi_lpc.c @@ -456,6 +456,17 @@ struct hisi_lpc_acpi_cell { size_t pdata_size; };

+static void hisi_lpc_acpi_remove(struct device *hostdev) +{ + struct acpi_device *adev = ACPI_COMPANION(hostdev); + struct acpi_device *child; + + device_for_each_child(hostdev, NULL, hisi_lpc_acpi_remove_subdev); + + list_for_each_entry(child, &adev->children, node) + acpi_device_clear_enumerated(child); +} + /* * hisi_lpc_acpi_probe - probe children for ACPI FW * @hostdev: LPC host device pointer @@ -555,8 +566,7 @@ static int hisi_lpc_acpi_probe(struct device *hostdev) return 0;

fail: - device_for_each_child(hostdev, NULL, - hisi_lpc_acpi_remove_subdev); + hisi_lpc_acpi_remove(hostdev); return ret; }

@@ -569,6 +579,10 @@ static int hisi_lpc_acpi_probe(struct device *dev) { return -ENODEV; } + +static void hisi_lpc_acpi_remove(struct device *hostdev) +{ +} #endif // CONFIG_ACPI

/* @@ -626,6 +640,8 @@ static int hisi_lpc_probe(struct platform_device *pdev) return ret; }

+ dev_set_drvdata(dev, lpcdev); + io_end = lpcdev->io_host->io_start + lpcdev->io_host->size; dev_info(dev, "registered range [%pa - %pa]\n", &lpcdev->io_host->io_start, &io_end); @@ -633,6 +649,23 @@ static int hisi_lpc_probe(struct platform_device *pdev) return ret; }

+static int hisi_lpc_remove(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct acpi_device *acpi_device = ACPI_COMPANION(dev); + struct hisi_lpc_dev *lpcdev = dev_get_drvdata(dev); + struct logic_pio_hwaddr *range = lpcdev->io_host; + + if (acpi_device) + hisi_lpc_acpi_remove(dev); + else + of_platform_depopulate(dev); + + logic_pio_unregister_range(range); + + return 0; +} + static const struct of_device_id hisi_lpc_of_match[] = { { .compatible = "hisilicon,hip06-lpc", }, { .compatible = "hisilicon,hip07-lpc", }, @@ -646,5 +679,6 @@ static struct platform_driver hisi_lpc_driver = { .acpi_match_table = ACPI_PTR(hisi_lpc_acpi_match), }, .probe = hisi_lpc_probe, + .remove = hisi_lpc_remove, }; builtin_platform_driver(hisi_lpc_driver);