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>

diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
index 477b62a74dbfee56c2eaabf4756d58a528b90f9d..59ec44175560811c72dbaa1c21c76dda3a2214c4 100644 (file)
--- 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)