Refactor the estatus queue's pool notification routine from
NOTIFY_NMI's handlers. This will allow another notification
method to use the estatus queue without duplicating this code.
Add 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.
in_nmi_queue_one_entry() 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 v7:
* Moved err= onto a separate line to make this more readable
* Dropped ghes_ prefix on new static functions
* Renamed stuff, 'notify' has an overloaded meaning,
Changes since v6:
* Removed pool grow/remove code as this is no longer necessary.
Changes since v3:
* Removed duplicate 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 | 65 ++++++++++++++++++++++++++--------------
1 file changed, 43 insertions(+), 22 deletions(-)
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index af3c10f47f20..cb3d88de711f 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -912,37 +912,58 @@ static void __process_error(struct ghes *ghes)
#endif
}
-static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
+static int ghes_in_nmi_queue_one_entry(struct ghes *ghes)
{
u64 buf_paddr;
- struct ghes *ghes;
- int sev, ret = NMI_DONE;
+ int sev;
- if (!atomic_add_unless(&ghes_in_nmi, 1, 1))
- return ret;
+ if (ghes_read_estatus(ghes, &buf_paddr)) {
+ ghes_clear_estatus(ghes, buf_paddr);
+ return -ENOENT;
+ }
- list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
- if (ghes_read_estatus(ghes, &buf_paddr)) {
- ghes_clear_estatus(ghes, buf_paddr);
- continue;
- } else {
- ret = NMI_HANDLED;
- }
+ sev = ghes_severity(ghes->estatus->error_severity);
+ if (sev >= GHES_SEV_PANIC) {
+ ghes_print_queued_estatus();
+ __ghes_panic(ghes, buf_paddr);
+ }
- sev = ghes_severity(ghes->estatus->error_severity);
- if (sev >= GHES_SEV_PANIC) {
- ghes_print_queued_estatus();
- __ghes_panic(ghes, buf_paddr);
- }
+ __process_error(ghes);
+ ghes_clear_estatus(ghes, buf_paddr);
- __process_error(ghes);
- ghes_clear_estatus(ghes, buf_paddr);
+ return 0;
+}
+
+static int ghes_in_nmi_spool_from_list(struct list_head *rcu_list)
+{
+ int err, ret = -ENOENT;
+ struct ghes *ghes;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(ghes, rcu_list, list) {
+ err = ghes_in_nmi_queue_one_entry(ghes);
+ if (!err)
+ ret = 0;
}
+ rcu_read_unlock();
-#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
- if (ret == NMI_HANDLED)
+ if (IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && !ret)
irq_work_queue(&ghes_proc_irq_work);
-#endif
+
+ return ret;
+}
+
+static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
+{
+ int err, ret = NMI_DONE;
+
+ if (!atomic_add_unless(&ghes_in_nmi, 1, 1))
+ return ret;
+
+ err = ghes_in_nmi_spool_from_list(&ghes_nmi);
+ if (!err)
+ ret = NMI_HANDLED;
+
atomic_dec(&ghes_in_nmi);
return ret;
}
--
2.20.1
