On 12/15/2009 05:25 PM, Boaz Harrosh wrote: > > Because of the terrible structuring of scsi-bidi-commands > it breaks some of the life time rules of a scsi-command. > It is now not allowed to free up the block-request before > cleanup and partial deallocation of the scsi-command. (Which > is not so for none bidi commands) > > The right fix to this problem would be to make bidi command > a first citizen by allocating a scsi_sdb pointer at scsi command > just like cmd->prot_sdb. The bidi sdb should be allocated/deallocated > as part of the get/put_command (Again like the prot_sdb) and the > current decoupling of scsi_cmnd and blk-request should be kept. > > For now make sure scsi_release_buffers() is called before the > call to blk_end_request_all() which might cause the suicide of > the block requests. At best the leak of bidi buffers, at worse > a crash, as there is a race between the existence of the bidi_request > and the free of the associated bidi_sdb. > > The reason this was never hit before is because only OSD has the potential > of doing asynchronous bidi commands. (So does bsg but it is never used) > And OSD clients just happen to do all their bidi commands synchronously, up > until recently. > > CC: Stable Tree <stable@xxxxxxxxxx> James hi. Have you had the chance on looking at this issue. It's a serious bug dated back a long time. Technically it is quite simple. It used to be: blk_end_request_all(req, 0); scsi_release_buffers(cmd); Now scsi_release_buffers tries to use cmd->req for inspecting the req->next pointer, but req was just freed by blk_end_request_all() Reversing the call to: scsi_release_buffers(cmd); blk_end_request_all(req, 0); Is the right thing to do and does not have any side effects what's so ever. Please put me out of my misery ;-) Boaz > Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx> > --- > drivers/scsi/scsi_lib.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 5987da8..bc9a881 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -749,9 +749,9 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) > */ > req->next_rq->resid_len = scsi_in(cmd)->resid; > > + scsi_release_buffers(cmd); > blk_end_request_all(req, 0); > > - scsi_release_buffers(cmd); > scsi_next_command(cmd); > return; > } -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
