Refactor the estatus queue's pool grow/shrink code and notification routine from NOTIFY_NMI's handlers. This will allow another notification method to use the estatus queue without duplicating this code. This patch adds rcu_read_lock()/rcu_read_unlock() around the list list_for_each_entry_rcu() walker. These aren't strictly necessary as the whole nmi_enter/nmi_exit() window is a spooky RCU read-side critical section. The existing ghes_estatus_pool_shrink() is folded into the new ghes_estatus_queue_shrink_pool() as only the queue uses it. _in_nmi_notify_one() is separate from the rcu-list walker for a later caller that doesn't need to walk a list. Signed-off-by: James Morse <james.morse@xxxxxxx> Reviewed-by: Punit Agrawal <punit.agrawal@xxxxxxx> Tested-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx> --- Changes since v3: * Removed dupicate or redundant paragraphs in commit message. * Fixed the style of a zero check Changes since v1: * Tidied up _in_nmi_notify_one(). --- drivers/acpi/apei/ghes.c | 100 +++++++++++++++++++++++++-------------- 1 file changed, 65 insertions(+), 35 deletions(-) diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index f5732e6b5be8..29d863ff2f87 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -747,6 +747,51 @@ static void __process_error(struct ghes *ghes) #endif } +static int _in_nmi_notify_one(struct ghes *ghes) +{ + int sev; + + if (ghes_read_estatus(ghes, 1)) { + ghes_clear_estatus(ghes); + return -ENOENT; + } + + sev = ghes_severity(ghes->estatus->error_severity); + if (sev >= GHES_SEV_PANIC) { +#ifdef CONFIG_X86 + oops_begin(); +#endif + ghes_print_queued_estatus(); + __ghes_panic(ghes); + } + + if (!(ghes->flags & GHES_TO_CLEAR)) + return 0; + + __process_error(ghes); + ghes_clear_estatus(ghes); + + return 0; +} + +static int ghes_estatus_queue_notified(struct list_head *rcu_list) +{ + int ret = -ENOENT; + struct ghes *ghes; + + rcu_read_lock(); + list_for_each_entry_rcu(ghes, rcu_list, list) { + if (!_in_nmi_notify_one(ghes)) + ret = 0; + } + rcu_read_unlock(); + + if (IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && !ret) + irq_work_queue(&ghes_proc_irq_work); + + return ret; +} + static unsigned long ghes_esource_prealloc_size( const struct acpi_hest_generic *generic) { @@ -762,11 +807,24 @@ static unsigned long ghes_esource_prealloc_size( return prealloc_size; } -static void ghes_estatus_pool_shrink(unsigned long len) +/* After removing a queue user, we can shrink the pool */ +static void ghes_estatus_queue_shrink_pool(struct ghes *ghes) { + unsigned long len; + + len = ghes_esource_prealloc_size(ghes->generic); ghes_estatus_pool_size_request -= PAGE_ALIGN(len); } +/* Before adding a queue user, grow the pool */ +static void ghes_estatus_queue_grow_pool(struct ghes *ghes) +{ + unsigned long len; + + len = ghes_esource_prealloc_size(ghes->generic); + ghes_estatus_pool_expand(len); +} + static void ghes_proc_in_irq(struct irq_work *irq_work) { struct llist_node *llnode, *next; @@ -965,48 +1023,22 @@ static LIST_HEAD(ghes_nmi); static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs) { - struct ghes *ghes; - int sev, ret = NMI_DONE; + int ret = NMI_DONE; if (!atomic_add_unless(&ghes_in_nmi, 1, 1)) return ret; - list_for_each_entry_rcu(ghes, &ghes_nmi, list) { - if (ghes_read_estatus(ghes, 1)) { - ghes_clear_estatus(ghes); - continue; - } else { - ret = NMI_HANDLED; - } - - sev = ghes_severity(ghes->estatus->error_severity); - if (sev >= GHES_SEV_PANIC) { - oops_begin(); - ghes_print_queued_estatus(); - __ghes_panic(ghes); - } + if (!ghes_estatus_queue_notified(&ghes_nmi)) + ret = NMI_HANDLED; - if (!(ghes->flags & GHES_TO_CLEAR)) - continue; - - __process_error(ghes); - ghes_clear_estatus(ghes); - } - -#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG - if (ret == NMI_HANDLED) - irq_work_queue(&ghes_proc_irq_work); -#endif atomic_dec(&ghes_in_nmi); return ret; } static void ghes_nmi_add(struct ghes *ghes) { - unsigned long len; + ghes_estatus_queue_grow_pool(ghes); - len = ghes_esource_prealloc_size(ghes->generic); - ghes_estatus_pool_expand(len); mutex_lock(&ghes_list_mutex); if (list_empty(&ghes_nmi)) register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0, "ghes"); @@ -1016,8 +1048,6 @@ static void ghes_nmi_add(struct ghes *ghes) static void ghes_nmi_remove(struct ghes *ghes) { - unsigned long len; - mutex_lock(&ghes_list_mutex); list_del_rcu(&ghes->list); if (list_empty(&ghes_nmi)) @@ -1028,8 +1058,8 @@ static void ghes_nmi_remove(struct ghes *ghes) * freed after NMI handler finishes. */ synchronize_rcu(); - len = ghes_esource_prealloc_size(ghes->generic); - ghes_estatus_pool_shrink(len); + + ghes_estatus_queue_shrink_pool(ghes); } #else /* CONFIG_HAVE_ACPI_APEI_NMI */ -- 2.17.1 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html