[SCSI] libata: reset once

Hotplug testing with libsas currently encounters a 55 second wait for
link recovery to give up.  In the case where the user trusts the
response time of their devices permit the recovery attempts to be
limited to one.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

4 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ad7e2e5088c1..2cb2d81a51ab 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1350,6 +1350,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         * nohrst, nosrst, norst: suppress hard, soft
                           and both resets.
 
+                        * rstonce: only attempt one reset during
+                          hot-unplug link recovery
+
                         * dump_id: dump IDENTIFY data.
 
                         If there are multiple matching configurations changing
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index fadd5866d40f..70964aabcb89 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6387,6 +6387,7 @@ static int __init ata_parse_force_one(char **cur,
                 { "nohrst",     .lflags         = ATA_LFLAG_NO_HRST },
                 { "nosrst",     .lflags         = ATA_LFLAG_NO_SRST },
                 { "norst",      .lflags         = ATA_LFLAG_NO_HRST | ATA_LFLAG_NO_SRST },
+                { "rstonce",    .lflags         = ATA_LFLAG_RST_ONCE },
         };
         char *start = *cur, *p = *cur;
         char *id, *val, *endp;
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 7d4535e989bf..100428dde421 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2623,6 +2623,8 @@ int ata_eh_reset(struct ata_link *link, int classify,
          */
         while (ata_eh_reset_timeouts[max_tries] != ULONG_MAX)
                 max_tries++;
+        if (link->flags & ATA_LFLAG_RST_ONCE)
+                max_tries = 1;
         if (link->flags & ATA_LFLAG_NO_HRST)
                 hardreset = NULL;
         if (link->flags & ATA_LFLAG_NO_SRST)
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 64f90e17e51d..31a2853e9530 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -184,6 +184,7 @@ enum {
         ATA_LFLAG_DISABLED      = (1 << 6), /* link is disabled */
         ATA_LFLAG_SW_ACTIVITY   = (1 << 7), /* keep activity stats */
         ATA_LFLAG_NO_LPM        = (1 << 8), /* disable LPM on this link */
+        ATA_LFLAG_RST_ONCE      = (1 << 9), /* limit recovery to one reset */
 
         /* struct ata_port flags */
         ATA_FLAG_SLAVE_POSS     = (1 << 0), /* host supports slave dev */