Messages in this thread Patch in this message | | | Date | Mon, 4 May 2015 11:33:47 +0200 | From | Borislav Petkov <> | Subject | [GIT PULL] RAS for 4.2 |
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Hi Ingo,
please queue for 4.2.
Thanks.
@Len, @Rafael: Guys, I'm sending this through tip even though strictly speaking it is ACPI.
I also am guessing to the point of being almost right, though, that you're secretly happy I'm doing that because it is one less issue you have to deal with. :-) :-)
Let me know if you still want to pick that up though.
Thanks.
--- The following changes since commit b787f68c36d49bb1d9236f403813641efa74a031:
Linux 4.1-rc1 (2015-04-26 17:59:10 -0700)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras.git tags/ras_for_4.2
for you to fetch changes up to 6fe9e7c26a97105645fd24f264f1b94e21aade3e:
GHES: Make NMI handler have a single reader (2015-04-27 21:35:33 +0200)
---------------------------------------------------------------- GHES: Seriously speedup and cleanup NMI handler (Jiri Kosina and Borislav Petkov)
This is the result of us seeing this during boot
[ 24.332560] INFO: NMI handler (ghes_notify_nmi) took too long to run: 3.265 msecs [ 24.332567] INFO: NMI handler (ghes_notify_nmi) took too long to run: 5.946 msecs [ 24.332568] INFO: NMI handler (ghes_notify_nmi) took too long to run: 5.948 msecs
and a report of people running perf stat and the machine softlocking. "hest_disable" was helping in this case, which made us look at that particular NMI handler. It was grabbing a lock each time it is run and on each CPU. But this is not needed as the GHES sources are global and they need only a single reader.
This patchset does that and cleans up the handler in the process.
---------------------------------------------------------------- Borislav Petkov (4): GHES: Carve out error queueing in a separate function GHES: Carve out the panic functionality GHES: Panic right after detection GHES: Elliminate double-loop in the NMI handler
Jiri Kosina (1): GHES: Make NMI handler have a single reader
drivers/acpi/apei/ghes.c | 108 ++++++++++++++++++++++++----------------------- 1 file changed, 55 insertions(+), 53 deletions(-)
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index e82d0976a5d0..2bfd53cbfe80 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -729,10 +729,10 @@ static struct llist_head ghes_estatus_llist; static struct irq_work ghes_proc_irq_work; /* - * NMI may be triggered on any CPU, so ghes_nmi_lock is used for - * mutual exclusion. + * NMI may be triggered on any CPU, so ghes_in_nmi is used for + * having only one concurrent reader. */ -static DEFINE_RAW_SPINLOCK(ghes_nmi_lock); +static atomic_t ghes_in_nmi = ATOMIC_INIT(0); static LIST_HEAD(ghes_nmi); @@ -797,73 +797,75 @@ static void ghes_print_queued_estatus(void) } } +/* Save estatus for further processing in IRQ context */ +static void __process_error(struct ghes *ghes) +{ +#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG + u32 len, node_len; + struct ghes_estatus_node *estatus_node; + struct acpi_hest_generic_status *estatus; + + if (ghes_estatus_cached(ghes->estatus)) + return; + + len = cper_estatus_len(ghes->estatus); + node_len = GHES_ESTATUS_NODE_LEN(len); + + estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len); + if (!estatus_node) + return; + + estatus_node->ghes = ghes; + estatus_node->generic = ghes->generic; + estatus = GHES_ESTATUS_FROM_NODE(estatus_node); + memcpy(estatus, ghes->estatus, len); + llist_add(&estatus_node->llnode, &ghes_estatus_llist); +#endif +} + +static void __ghes_panic(struct ghes *ghes) +{ + oops_begin(); + ghes_print_queued_estatus(); + __ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus); + + /* reboot to log the error! */ + if (panic_timeout == 0) + panic_timeout = ghes_panic_timeout; + panic("Fatal hardware error!"); +} + static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs) { - struct ghes *ghes, *ghes_global = NULL; - int sev, sev_global = -1; - int ret = NMI_DONE; + struct ghes *ghes; + int sev, ret = NMI_DONE; + + if (!atomic_add_unless(&ghes_in_nmi, 1, 1)) + return ret; - raw_spin_lock(&ghes_nmi_lock); list_for_each_entry_rcu(ghes, &ghes_nmi, list) { if (ghes_read_estatus(ghes, 1)) { ghes_clear_estatus(ghes); continue; } - sev = ghes_severity(ghes->estatus->error_severity); - if (sev > sev_global) { - sev_global = sev; - ghes_global = ghes; - } - ret = NMI_HANDLED; - } - - if (ret == NMI_DONE) - goto out; - if (sev_global >= GHES_SEV_PANIC) { - oops_begin(); - ghes_print_queued_estatus(); - __ghes_print_estatus(KERN_EMERG, ghes_global->generic, - ghes_global->estatus); - /* reboot to log the error! */ - if (panic_timeout == 0) - panic_timeout = ghes_panic_timeout; - panic("Fatal hardware error!"); - } + sev = ghes_severity(ghes->estatus->error_severity); + if (sev >= GHES_SEV_PANIC) + __ghes_panic(ghes); - list_for_each_entry_rcu(ghes, &ghes_nmi, list) { -#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG - u32 len, node_len; - struct ghes_estatus_node *estatus_node; - struct acpi_hest_generic_status *estatus; -#endif if (!(ghes->flags & GHES_TO_CLEAR)) continue; -#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG - if (ghes_estatus_cached(ghes->estatus)) - goto next; - /* Save estatus for further processing in IRQ context */ - len = cper_estatus_len(ghes->estatus); - node_len = GHES_ESTATUS_NODE_LEN(len); - estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, - node_len); - if (estatus_node) { - estatus_node->ghes = ghes; - estatus_node->generic = ghes->generic; - estatus = GHES_ESTATUS_FROM_NODE(estatus_node); - memcpy(estatus, ghes->estatus, len); - llist_add(&estatus_node->llnode, &ghes_estatus_llist); - } -next: -#endif + + __process_error(ghes); ghes_clear_estatus(ghes); + + ret = NMI_HANDLED; } + #ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG irq_work_queue(&ghes_proc_irq_work); #endif - -out: - raw_spin_unlock(&ghes_nmi_lock); + atomic_dec(&ghes_in_nmi); return ret; } -- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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