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authorEddie Wai <eddie.wai@broadcom.com>2011-07-15 22:17:26 +0400
committerJames Bottomley <JBottomley@Parallels.com>2011-07-22 01:03:27 +0400
commit0d83ab65ff1b54ce8b6cd172285cf71a38c4cceb (patch)
treec39185fbe3cc254a077643e5ef91d507ff8fceba /drivers/scsi/bnx2i
parent2dabc55dfe655390a7bfd346e595c33ee2f2cc82 (diff)
downloadlinux-0d83ab65ff1b54ce8b6cd172285cf71a38c4cceb.tar.xz
[SCSI] bnx2i: Fixed kernel panic due to illegal usage of sc->request->cpu
A kernel panic was observed when passing the sc->request->cpu = -1 to retrieve the per_cpu variable pointer: #0 [ffff880011203960] machine_kexec at ffffffff81022bc3 #1 [ffff8800112039b0] crash_kexec at ffffffff81088630 #2 [ffff880011203a80] __die at ffffffff8139ea20 #3 [ffff880011203aa0] no_context at ffffffff8102f3a7 #4 [ffff880011203ae0] __bad_area_nosemaphore at ffffffff8102f665 #5 [ffff880011203ba0] retint_signal at ffffffff8139dd1f #6 [ffff880011203cc8] bnx2i_indicate_kcqe at ffffffffa03dc4f2 #7 [ffff880011203da8] service_kcqes at ffffffffa03cb04f #8 [ffff880011203e68] cnic_service_bnx2x_kcq at ffffffffa03cb14a #9 [ffff880011203e88] cnic_service_bnx2x_bh at ffffffffa03cb1b3 The problem lies in the slow path sg_io (and perhaps sg_scsi_ioctl) call to blk_get_request->get_request/wait->blk_alloc_request->blk_rq_init which re-initializes the request->cpu to -1. There is no assignment for cpu from that to the request_fn call to low level drivers. When this happens, the sc->request->cpu will be using the init value of -1. This will create a kernel panic when it hits bnx2i because the code refers it to get the per_cpu variables ptr. This change is to put in a guard against that and also for cases when bio affinity/queue completion to the same cpu is not enabled. In those cases, the request->cpu will remain a -1 also. This bug was created from commit: b5cf6b63f73abdc051035f0050b367beeb2ef94c For the case when the blk layer did not setup the request->cpu, bnx2i will complete the sc with the current CPU of the thread. Signed-off-by: Eddie Wai <eddie.wai@broadcom.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi/bnx2i')
-rw-r--r--drivers/scsi/bnx2i/bnx2i_hwi.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/scsi/bnx2i/bnx2i_hwi.c b/drivers/scsi/bnx2i/bnx2i_hwi.c
index 54978c1de159..28c6693688d8 100644
--- a/drivers/scsi/bnx2i/bnx2i_hwi.c
+++ b/drivers/scsi/bnx2i/bnx2i_hwi.c
@@ -1901,6 +1901,7 @@ static int bnx2i_queue_scsi_cmd_resp(struct iscsi_session *session,
struct iscsi_task *task;
struct scsi_cmnd *sc;
int rc = 0;
+ int cpu;
spin_lock(&session->lock);
task = iscsi_itt_to_task(bnx2i_conn->cls_conn->dd_data,
@@ -1912,7 +1913,12 @@ static int bnx2i_queue_scsi_cmd_resp(struct iscsi_session *session,
sc = task->sc;
spin_unlock(&session->lock);
- p = &per_cpu(bnx2i_percpu, sc->request->cpu);
+ if (!blk_rq_cpu_valid(sc->request))
+ cpu = smp_processor_id();
+ else
+ cpu = sc->request->cpu;
+
+ p = &per_cpu(bnx2i_percpu, cpu);
spin_lock(&p->p_work_lock);
if (unlikely(!p->iothread)) {
rc = -EINVAL;