[PATCH] dpt_i2o fix for deadlock condition

Miquel van Smoorenburg <miquels@cistron.nl> forwarded me this fix to
resolve a deadlock condition that occurs due to the API change in
2.6.13+ kernels dropping the host locking when entering the error
handling.  They all end up calling adpt_i2o_post_wait(), which if you
call it unlocked, might return with host_lock locked anyway and that
causes a deadlock.

Signed-off-by: Mark Salyzyn <aacraid@adaptec.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/scsi/dpt_i2o.c b/drivers/scsi/dpt_i2o.c
index 418fc7b896ac..6252b9ddc01e 100644
--- a/drivers/scsi/dpt_i2o.c
+++ b/drivers/scsi/dpt_i2o.c
@@ -660,7 +660,12 @@ static int adpt_abort(struct scsi_cmnd * cmd)
         msg[2] = 0;
         msg[3]= 0; 
         msg[4] = (u32)cmd;
-        if( (rcode = adpt_i2o_post_wait(pHba, msg, sizeof(msg), FOREVER)) != 0){
+        if (pHba->host)
+                spin_lock_irq(pHba->host->host_lock);
+        rcode = adpt_i2o_post_wait(pHba, msg, sizeof(msg), FOREVER);
+        if (pHba->host)
+                spin_unlock_irq(pHba->host->host_lock);
+        if (rcode != 0) {
                 if(rcode == -EOPNOTSUPP ){
                         printk(KERN_INFO"%s: Abort cmd not supported\n",pHba->name);
                         return FAILED;
@@ -697,10 +702,15 @@ static int adpt_device_reset(struct scsi_cmnd* cmd)
         msg[2] = 0;
         msg[3] = 0;
 
+        if (pHba->host)
+                spin_lock_irq(pHba->host->host_lock);
         old_state = d->state;
         d->state |= DPTI_DEV_RESET;
-        if( (rcode = adpt_i2o_post_wait(pHba, msg,sizeof(msg), FOREVER)) ){
-                d->state = old_state;
+        rcode = adpt_i2o_post_wait(pHba, msg,sizeof(msg), FOREVER);
+        d->state = old_state;
+        if (pHba->host)
+                spin_unlock_irq(pHba->host->host_lock);
+        if (rcode != 0) {
                 if(rcode == -EOPNOTSUPP ){
                         printk(KERN_INFO"%s: Device reset not supported\n",pHba->name);
                         return FAILED;
@@ -708,7 +718,6 @@ static int adpt_device_reset(struct scsi_cmnd* cmd)
                 printk(KERN_INFO"%s: Device reset failed\n",pHba->name);
                 return FAILED;
         } else {
-                d->state = old_state;
                 printk(KERN_INFO"%s: Device reset successful\n",pHba->name);
                 return SUCCESS;
         }
@@ -721,6 +730,7 @@ static int adpt_bus_reset(struct scsi_cmnd* cmd)
 {
         adpt_hba* pHba;
         u32 msg[4];
+        u32 rcode;
 
         pHba = (adpt_hba*)cmd->device->host->hostdata[0];
         memset(msg, 0, sizeof(msg));
@@ -729,7 +739,12 @@ static int adpt_bus_reset(struct scsi_cmnd* cmd)
         msg[1] = (I2O_HBA_BUS_RESET<<24|HOST_TID<<12|pHba->channel[cmd->device->channel].tid);
         msg[2] = 0;
         msg[3] = 0;
-        if(adpt_i2o_post_wait(pHba, msg,sizeof(msg), FOREVER) ){
+        if (pHba->host)
+                spin_lock_irq(pHba->host->host_lock);
+        rcode = adpt_i2o_post_wait(pHba, msg,sizeof(msg), FOREVER);
+        if (pHba->host)
+                spin_unlock_irq(pHba->host->host_lock);
+        if (rcode != 0) {
                 printk(KERN_WARNING"%s: Bus reset failed.\n",pHba->name);
                 return FAILED;
         } else {