i7core_edac: First store, then increment

Fix ringbuffer store logic.

While here, add a few comments to the code and remove the undesired
printk that could otherwise be called during NMI time.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
index 477b62a74dbf..59ec44175560 100644
--- a/drivers/edac/i7core_edac.c
+++ b/drivers/edac/i7core_edac.c
@@ -1678,6 +1678,8 @@ static void i7core_check_error(struct mem_ctl_info *mci)
  *                              This routine simply queues mcelog errors, and
  *                              return. The error itself should be handled later
  *                              by i7core_check_error.
+ * WARNING: As this routine should be called at NMI time, extra care should
+ * be taken to avoid deadlocks, and to be as fast as possible.
  */
 static int i7core_mce_check_error(void *priv, struct mce *mce)
 {
@@ -1696,13 +1698,8 @@ static int i7core_mce_check_error(void *priv, struct mce *mce)
                 return 0;
 
         /* Only handle if it is the right mc controller */
-        if (cpu_data(mce->cpu).phys_proc_id != pvt->i7core_dev->socket) {
-                debugf0("mc%d: ignoring mce log for socket %d. "
-                        "Another mc should get it.\n",
-                        pvt->i7core_dev->socket,
-                        cpu_data(mce->cpu).phys_proc_id);
+        if (cpu_data(mce->cpu).phys_proc_id != pvt->i7core_dev->socket)
                 return 0;
-        }
 
         smp_rmb();
         if ((pvt->mce_out + 1) % sizeof(mce_entry) == pvt->mce_in) {
@@ -1710,9 +1707,11 @@ static int i7core_mce_check_error(void *priv, struct mce *mce)
                 pvt->mce_overrun++;
                 return 0;
         }
+
+        /* Copy memory error at the ringbuffer */
+        memcpy(&pvt->mce_entry[pvt->mce_out], mce, sizeof(*mce));
         smp_wmb();
         pvt->mce_out = (pvt->mce_out + 1) % sizeof(mce_entry);
-        memcpy(&pvt->mce_entry[pvt->mce_out], mce, sizeof(*mce));
 
         /* Handle fatal errors immediately */
         if (mce->mcgstatus & 1)