4.18-stable review patch. If anyone has any objections, please let me know.
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From: Selvin Xavier selvin.xavier@broadcom.com
[ Upstream commit d455f29f6d76a5f94881ca1289aaa1e90617ff5d ]
Fix possible recursive lock warning. Its a false warning as the locks are part of two differnt HW Queue data structure - cmdq and creq. Debug kernel is throwing the following warning and stack trace.
[ 783.914967] ============================================ [ 783.914970] WARNING: possible recursive locking detected [ 783.914973] 4.19.0-rc2+ #33 Not tainted [ 783.914976] -------------------------------------------- [ 783.914979] swapper/2/0 is trying to acquire lock: [ 783.914982] 000000002aa3949d (&(&hwq->lock)->rlock){..-.}, at: bnxt_qplib_service_creq+0x232/0x350 [bnxt_re] [ 783.914999] but task is already holding lock: [ 783.915002] 00000000be73920d (&(&hwq->lock)->rlock){..-.}, at: bnxt_qplib_service_creq+0x2a/0x350 [bnxt_re] [ 783.915013] other info that might help us debug this: [ 783.915016] Possible unsafe locking scenario:
[ 783.915019] CPU0 [ 783.915021] ---- [ 783.915034] lock(&(&hwq->lock)->rlock); [ 783.915035] lock(&(&hwq->lock)->rlock); [ 783.915037] *** DEADLOCK ***
[ 783.915038] May be due to missing lock nesting notation
[ 783.915039] 1 lock held by swapper/2/0: [ 783.915040] #0: 00000000be73920d (&(&hwq->lock)->rlock){..-.}, at: bnxt_qplib_service_creq+0x2a/0x350 [bnxt_re] [ 783.915044] stack backtrace: [ 783.915046] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.19.0-rc2+ #33 [ 783.915047] Hardware name: Dell Inc. PowerEdge R730/0599V5, BIOS 1.0.4 08/28/2014 [ 783.915048] Call Trace: [ 783.915049] <IRQ> [ 783.915054] dump_stack+0x90/0xe3 [ 783.915058] __lock_acquire+0x106c/0x1080 [ 783.915061] ? sched_clock+0x5/0x10 [ 783.915063] lock_acquire+0xbd/0x1a0 [ 783.915065] ? bnxt_qplib_service_creq+0x232/0x350 [bnxt_re] [ 783.915069] _raw_spin_lock_irqsave+0x4a/0x90 [ 783.915071] ? bnxt_qplib_service_creq+0x232/0x350 [bnxt_re] [ 783.915073] bnxt_qplib_service_creq+0x232/0x350 [bnxt_re] [ 783.915078] tasklet_action_common.isra.17+0x197/0x1b0 [ 783.915081] __do_softirq+0xcb/0x3a6 [ 783.915084] irq_exit+0xe9/0x100 [ 783.915085] do_IRQ+0x6a/0x120 [ 783.915087] common_interrupt+0xf/0xf [ 783.915088] </IRQ>
Use nested notation for the spin_lock to avoid this warning.
Signed-off-by: Selvin Xavier selvin.xavier@broadcom.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/infiniband/hw/bnxt_re/qplib_rcfw.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c +++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c @@ -309,8 +309,17 @@ static int bnxt_qplib_process_qp_event(s rcfw->aeq_handler(rcfw, qp_event, qp); break; default: - /* Command Response */ - spin_lock_irqsave(&cmdq->lock, flags); + /* + * Command Response + * cmdq->lock needs to be acquired to synchronie + * the command send and completion reaping. This function + * is always called with creq->lock held. Using + * the nested variant of spin_lock. + * + */ + + spin_lock_irqsave_nested(&cmdq->lock, flags, + SINGLE_DEPTH_NESTING); cookie = le16_to_cpu(qp_event->cookie); mcookie = qp_event->cookie; blocked = cookie & RCFW_CMD_IS_BLOCKING;