[PATCH v2 02/11] scsi: Drop struct Scsi_Host->host_lock usage in scsi_dispatch_cmd()

From: Nicholas A. Bellinger
Date: Fri Sep 17 2010 - 14:22:13 EST


From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

This patch converts scsi_dispatch_cmd() to no longer lock() + unlock()
struct Scsi_Host->host_lock while calling scsi_cmd_get_serial() and
SHT->queuecommand() dispatcher. This patch follows commit 5900e428420d
which means we can now safely call scsi_cmd_get_serial() without the
host_lock held.

Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/scsi/scsi.c | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 4724ce7..d1aa209 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -658,7 +658,6 @@ static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
struct Scsi_Host *host = cmd->device->host;
- unsigned long flags = 0;
unsigned long timeout;
int rtn = 0;

@@ -744,7 +743,6 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
goto out;
}

- spin_lock_irqsave(host->host_lock, flags);
/*
* AK: unlikely race here: for some reason the timer could
* expire before the serial number is set up below.
@@ -760,7 +758,7 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
trace_scsi_dispatch_cmd_start(cmd);
rtn = host->hostt->queuecommand(cmd, scsi_done);
}
- spin_unlock_irqrestore(host->host_lock, flags);
+
if (rtn) {
trace_scsi_dispatch_cmd_error(cmd, rtn);
if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
--
1.7.2.3

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