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IB/srp: Fix a race condition

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Avoid a crash caused by the scmnd->scsi_done(scmnd) call in
srp_process_rsp() being invoked with scsi_done == NULL.  This can
happen if a reply is received during or after a command abort.

Reported-by: Joseph Glanville <joseph.glanville@orionvm.com.au>
Reference: http://marc.info/?l=linux-rdma&m=134314367801595
Cc: <stable@vger.kernel.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
This commit is contained in:
Bart Van Assche 2012-08-14 13:18:53 +00:00 committed by Roland Dreier
parent 0d7614f09c
commit 220329916c
1 changed files with 63 additions and 24 deletions
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87
drivers/infiniband/ulp/srp/ib_srp.c
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@ -586,24 +586,62 @@ static void srp_unmap_data(struct scsi_cmnd *scmnd,
scmnd->sc_data_direction);
}
static void srp_remove_req(struct srp_target_port *target,
struct srp_request *req, s32 req_lim_delta)
/**
* srp_claim_req - Take ownership of the scmnd associated with a request.
* @target: SRP target port.
* @req: SRP request.
* @scmnd: If NULL, take ownership of @req->scmnd. If not NULL, only take
* ownership of @req->scmnd if it equals @scmnd.
*
* Return value:
* Either NULL or a pointer to the SCSI command the caller became owner of.
*/
static struct scsi_cmnd *srp_claim_req(struct srp_target_port *target,
struct srp_request *req,
struct scsi_cmnd *scmnd)
{
unsigned long flags;
srp_unmap_data(req->scmnd, target, req);
spin_lock_irqsave(&target->lock, flags);
if (!scmnd) {
scmnd = req->scmnd;
req->scmnd = NULL;
} else if (req->scmnd == scmnd) {
req->scmnd = NULL;
} else {
scmnd = NULL;
}
spin_unlock_irqrestore(&target->lock, flags);
return scmnd;
}
/**
* srp_free_req() - Unmap data and add request to the free request list.
*/
static void srp_free_req(struct srp_target_port *target,
struct srp_request *req, struct scsi_cmnd *scmnd,
s32 req_lim_delta)
{
unsigned long flags;
srp_unmap_data(scmnd, target, req);
spin_lock_irqsave(&target->lock, flags);
target->req_lim += req_lim_delta;
req->scmnd = NULL;
list_add_tail(&req->list, &target->free_reqs);
spin_unlock_irqrestore(&target->lock, flags);
}
static void srp_reset_req(struct srp_target_port *target, struct srp_request *req)
{
req->scmnd->result = DID_RESET << 16;
req->scmnd->scsi_done(req->scmnd);
srp_remove_req(target, req, 0);
struct scsi_cmnd *scmnd = srp_claim_req(target, req, NULL);
if (scmnd) {
scmnd->result = DID_RESET << 16;
scmnd->scsi_done(scmnd);
srp_free_req(target, req, scmnd, 0);
}
}
static int srp_reconnect_target(struct srp_target_port *target)
@ -1073,11 +1111,18 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
complete(&target->tsk_mgmt_done);
} else {
req = &target->req_ring[rsp->tag];
scmnd = req->scmnd;
if (!scmnd)
scmnd = srp_claim_req(target, req, NULL);
if (!scmnd) {
shost_printk(KERN_ERR, target->scsi_host,
"Null scmnd for RSP w/tag %016llx\n",
(unsigned long long) rsp->tag);
spin_lock_irqsave(&target->lock, flags);
target->req_lim += be32_to_cpu(rsp->req_lim_delta);
spin_unlock_irqrestore(&target->lock, flags);
return;
}
scmnd->result = rsp->status;
if (rsp->flags & SRP_RSP_FLAG_SNSVALID) {
@ -1092,7 +1137,9 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
else if (rsp->flags & (SRP_RSP_FLAG_DIOVER | SRP_RSP_FLAG_DIUNDER))
scsi_set_resid(scmnd, be32_to_cpu(rsp->data_in_res_cnt));
srp_remove_req(target, req, be32_to_cpu(rsp->req_lim_delta));
srp_free_req(target, req, scmnd,
be32_to_cpu(rsp->req_lim_delta));
scmnd->host_scribble = NULL;
scmnd->scsi_done(scmnd);
}
@ -1631,25 +1678,17 @@ static int srp_abort(struct scsi_cmnd *scmnd)
{
struct srp_target_port *target = host_to_target(scmnd->device->host);
struct srp_request *req = (struct srp_request *) scmnd->host_scribble;
int ret = SUCCESS;
shost_printk(KERN_ERR, target->scsi_host, "SRP abort called\n");
if (!req || target->qp_in_error)
return FAILED;
if (srp_send_tsk_mgmt(target, req->index, scmnd->device->lun,
SRP_TSK_ABORT_TASK))
if (!req || target->qp_in_error || !srp_claim_req(target, req, scmnd))
return FAILED;
srp_send_tsk_mgmt(target, req->index, scmnd->device->lun,
SRP_TSK_ABORT_TASK);
srp_free_req(target, req, scmnd, 0);
scmnd->result = DID_ABORT << 16;
if (req->scmnd) {
if (!target->tsk_mgmt_status) {
srp_remove_req(target, req, 0);
scmnd->result = DID_ABORT << 16;
} else
ret = FAILED;
}
return ret;
return SUCCESS;
}
static int srp_reset_device(struct scsi_cmnd *scmnd)