libata: only ports >= 0 need to synchronize

In a discussio with Jeff Garzik, he mentioned that the serialization
for the libata port probes only needs to be within the domain of a host.
This means that for the first port of each host (with ID 0), we don't
need to wait, so we can relax our serialization a little.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index f810078fafcc..71218d76d75e 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5925,8 +5925,10 @@ static void async_port_probe(void *data, async_cookie_t cookie)
          * If we're not allowed to scan this host in parallel,
          * we need to wait until all previous scans have completed
          * before going further.
+         * Jeff Garzik says this is only within a controller, so we
+         * don't need to wait for port 0, only for later ports.
          */
-        if (!(ap->host->flags & ATA_HOST_PARALLEL_SCAN))
+        if (!(ap->host->flags & ATA_HOST_PARALLEL_SCAN) && ap->port_no != 0)
                 async_synchronize_cookie(cookie);
 
         /* probe */