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Date: Sun, 09 Sep 2012 23:42:23 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
alan@...rguk.ukuu.org.uk, Bart Van Assche <bvanassche@....org>,
Joseph Glanville <joseph.glanville@...onvm.com.au>,
David Dillow <dillowda@...l.gov>,
Roland Dreier <roland@...estorage.com>
Subject: [ 33/95] IB/srp: Fix a race condition
3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bart Van Assche <bvanassche@....org>
commit 220329916c72ee3d54ae7262b215a050f04a18fc upstream.
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@...onvm.com.au>
Reference: http://marc.info/?l=linux-rdma&m=134314367801595
Acked-by: David Dillow <dillowda@...l.gov>
Signed-off-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Roland Dreier <roland@...estorage.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
drivers/infiniband/ulp/srp/ib_srp.c | 87 +++++++++++++++++++++++++----------
1 file changed, 63 insertions(+), 24 deletions(-)
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index bcbf22e..1b5b0c7 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -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;
+
+ 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(req->scmnd, target, req);
+ 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)
+ if (!req || target->qp_in_error || !srp_claim_req(target, req, scmnd))
return FAILED;
- if (srp_send_tsk_mgmt(target, req->index, scmnd->device->lun,
- SRP_TSK_ABORT_TASK))
- return FAILED;
-
- if (req->scmnd) {
- if (!target->tsk_mgmt_status) {
- srp_remove_req(target, req, 0);
- scmnd->result = DID_ABORT << 16;
- } else
- ret = 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;
- return ret;
+ return SUCCESS;
}
static int srp_reset_device(struct scsi_cmnd *scmnd)
--
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