libata: skip old error history when counting probe trials

BugLink: http://bugs.launchpad.net/bugs/996109

commit 6868225e3e92399068be9a5f1635752d91012ad5 upstream.

Commit d902747("[libata] Add ATA transport class") introduced
ATA_EFLAG_OLD_ER to mark entries in the error ring as cleared.

But ata_count_probe_trials_cb() didn't check this flag and it still
counts the old error history. So wrong probe trials count is returned
and it causes problem, for example, SATA link speed is slowed down from
3.0Gbps to 1.5Gbps.

Fix it by checking ATA_EFLAG_OLD_ER in ata_count_probe_trials_cb().

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 7f099d6e4e0..311c92d1db2 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3487,7 +3487,8 @@ static int ata_count_probe_trials_cb(struct ata_ering_entry *ent, void *void_arg
         u64 now = get_jiffies_64();
         int *trials = void_arg;
 
-        if (ent->timestamp < now - min(now, interval))
+        if ((ent->eflags & ATA_EFLAG_OLD_ER) ||
+            (ent->timestamp < now - min(now, interval)))
                 return -1;
 
         (*trials)++;