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bug in IBM ServeRAID driver?

DISCUSSION petter wahlman 2 participants 2 messages Jan 3, 2002

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#0 lore raw

While looking through linux-2.4.18pre1/drivers/scsi/ips.c I noticed that a spin_lock_irq is held while doing a possibly blocking operation. Can't this code livelock on SMP if datasize is set?

linux-2.4.18pre1/drivers/scsi/ips.c

1778 /* reobtain the lock */
1779 spin_lock_irq(&io_request_lock);
1780

   1781       /* command finished -- copy back */
   1782       user_area = *((char **) &SC->cmnd[4]);
   1783       kern_area = ha->ioctl_data;
   1784       datasize = *((u_int32_t *) &SC->cmnd[8]);

1785
1786 if (datasize) {
1787 if (copy_to_user(user_area, kern_area, datasize) > 0) {
1788 DEBUG_VAR(1, "(%s%d) passthru failed - unable to
copy out user data",
1789 ips_name, ha->host_num);

I am not subscribed to this list, so please CC me.

Petter Wahlman

#1 lore raw
Quoted 18 lines · petter wahlman

While looking through linux-2.4.18pre1/drivers/scsi/ips.c I noticed that a spin_lock_irq is held while doing a possibly blocking operation. Can't this code livelock on SMP if datasize is set?

linux-2.4.18pre1/drivers/scsi/ips.c

   1778       /* reobtain the lock */
   1779       spin_lock_irq(&io_request_lock);
   1780
   1781       /* command finished -- copy back */
   1782       user_area = *((char **) &SC->cmnd[4]);
   1783       kern_area = ha->ioctl_data;
   1784       datasize = *((u_int32_t *) &SC->cmnd[8]);
   1785
   1786       if (datasize) {
   1787          if (copy_to_user(user_area, kern_area, datasize) > 0) {
   1788             DEBUG_VAR(1, "(%s%d) passthru failed - unable to
Quoted 5 lines

copy out user data",
1789 ips_name, ha->host_num);

I am not subscribed to this list, so please CC me.

Yup, that's surely a nasty bug.

Signature · 1 line
Jens Axboe