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IB/srp: Fix a race condition between failing I/O and I/O completion 

Avoid that srp_terminate_io() can access req->scmnd after it has been
cleared by the I/O completion code. Do this by protecting req->scmnd
accesses from srp_terminate_io() via locking

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
This commit is contained in:
Bart Van Assche 2014-03-14 13:54:11 +01:00 committed by Roland Dreier
parent ac72d766a8
commit b3fe628da2
1 changed files with 22 additions and 11 deletions
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33
drivers/infiniband/ulp/srp/ib_srp.c
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@ -783,6 +783,7 @@ static void srp_unmap_data(struct scsi_cmnd *scmnd,
* srp_claim_req - Take ownership of the scmnd associated with a request.
* @target: SRP target port.
* @req: SRP request.
* @sdev: If not NULL, only take ownership for this SCSI device.
* @scmnd: If NULL, take ownership of @req->scmnd. If not NULL, only take
* ownership of @req->scmnd if it equals @scmnd.
*
@ -791,16 +792,17 @@ static void srp_unmap_data(struct scsi_cmnd *scmnd,
*/
static struct scsi_cmnd *srp_claim_req(struct srp_target_port *target,
struct srp_request *req,
struct scsi_device *sdev,
struct scsi_cmnd *scmnd)
{
unsigned long flags;
spin_lock_irqsave(&target->lock, flags);
if (!scmnd) {
if (req->scmnd &&
(!sdev || req->scmnd->device == sdev) &&
(!scmnd || req->scmnd == scmnd)) {
scmnd = req->scmnd;
req->scmnd = NULL;
} else if (req->scmnd == scmnd) {
req->scmnd = NULL;
} else {
scmnd = NULL;
}
@ -827,9 +829,10 @@ static void srp_free_req(struct srp_target_port *target,
}
static void srp_finish_req(struct srp_target_port *target,
struct srp_request *req, int result)
struct srp_request *req, struct scsi_device *sdev,
int result)
{
struct scsi_cmnd *scmnd = srp_claim_req(target, req, NULL);
struct scsi_cmnd *scmnd = srp_claim_req(target, req, sdev, NULL);
if (scmnd) {
srp_free_req(target, req, scmnd, 0);
@ -841,11 +844,20 @@ static void srp_finish_req(struct srp_target_port *target,
static void srp_terminate_io(struct srp_rport *rport)
{
struct srp_target_port *target = rport->lld_data;
struct Scsi_Host *shost = target->scsi_host;
struct scsi_device *sdev;
int i;
/*
* Invoking srp_terminate_io() while srp_queuecommand() is running
* is not safe. Hence the warning statement below.
*/
shost_for_each_device(sdev, shost)
WARN_ON_ONCE(sdev->request_queue->request_fn_active);
for (i = 0; i < target->req_ring_size; ++i) {
struct srp_request *req = &target->req_ring[i];
srp_finish_req(target, req, DID_TRANSPORT_FAILFAST << 16);
srp_finish_req(target, req, NULL, DID_TRANSPORT_FAILFAST << 16);
}
}
@ -882,7 +894,7 @@ static int srp_rport_reconnect(struct srp_rport *rport)
for (i = 0; i < target->req_ring_size; ++i) {
struct srp_request *req = &target->req_ring[i];
srp_finish_req(target, req, DID_RESET << 16);
srp_finish_req(target, req, NULL, DID_RESET << 16);
}
INIT_LIST_HEAD(&target->free_tx);
@ -1290,7 +1302,7 @@ 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 = srp_claim_req(target, req, NULL);
scmnd = srp_claim_req(target, req, NULL, NULL);
if (!scmnd) {
shost_printk(KERN_ERR, target->scsi_host,
"Null scmnd for RSP w/tag %016llx\n",
@ -2008,7 +2020,7 @@ static int srp_abort(struct scsi_cmnd *scmnd)
shost_printk(KERN_ERR, target->scsi_host, "SRP abort called\n");
if (!req || !srp_claim_req(target, req, scmnd))
if (!req || !srp_claim_req(target, req, NULL, scmnd))
return SUCCESS;
if (srp_send_tsk_mgmt(target, req->index, scmnd->device->lun,
SRP_TSK_ABORT_TASK) == 0)
@ -2039,8 +2051,7 @@ static int srp_reset_device(struct scsi_cmnd *scmnd)
for (i = 0; i < target->req_ring_size; ++i) {
struct srp_request *req = &target->req_ring[i];
if (req->scmnd && req->scmnd->device == scmnd->device)
srp_finish_req(target, req, DID_RESET << 16);
srp_finish_req(target, req, scmnd->device, DID_RESET << 16);
}
return SUCCESS;