[PATCH 1/8] x86/mce: Stop mce_reign() from re-computing severity for every CPU

Tony Luck
2020-09-08T17:56:40Z

Back in:

commit 20d51a426fe9 ("x86/mce: Reuse one of the u16 padding fields in 'struct mce'")

a field was added to "struct mce" to save the computed error severity.

Make use of this in mce_reign() to avoid re-computing the severity
for every CPU.

In the case where we panic, we do still need one call to mce_severity to
provide the correct message giving the reason for the panic.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index f43a78bde670..fb6b5f64f7e6 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -872,7 +872,6 @@ static void mce_reign(void)
struct mce *m = NULL;
int global_worst = 0;
char *msg = NULL;
- char *nmsg = NULL;

/*
* This CPU is the Monarch and the other CPUs have run
@@ -880,12 +879,10 @@ static void mce_reign(void)
* Grade the severity of the errors of all the CPUs.
*/
for_each_possible_cpu(cpu) {
- int severity = mce_severity(&per_cpu(mces_seen, cpu),
- mca_cfg.tolerant,
- &nmsg, true);
- if (severity > global_worst) {
- msg = nmsg;
- global_worst = severity;
+ struct mce *mtmp = &per_cpu(mces_seen, cpu);
+
+ if (mtmp->severity > global_worst) {
+ global_worst = mtmp->severity;
m = &per_cpu(mces_seen, cpu);
}
}
@@ -895,8 +892,11 @@ static void mce_reign(void)
* This dumps all the mces in the log buffer and stops the
* other CPUs.
*/
- if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3)
+ if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) {
+ /* call mce_severity() to get "msg" for panic */
+ mce_severity(m, mca_cfg.tolerant, &msg, true);
mce_panic("Fatal machine check", m, msg);
+ }

/*
* For UC somewhere we let the CPU who detects it handle it.
--
2.21.1