| Message ID | 1624329292-27092-1-git-send-email-bbhatt@codeaurora.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | [v2] bus: mhi: core: Disable pre-emption for events tasklet processing | expand |
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c index 3775c77..02c8c09 100644 --- a/drivers/bus/mhi/core/main.c +++ b/drivers/bus/mhi/core/main.c @@ -1036,11 +1036,12 @@ void mhi_ev_task(unsigned long data) { struct mhi_event *mhi_event = (struct mhi_event *)data; struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl; + unsigned long flags; /* process all pending events */ - spin_lock_bh(&mhi_event->lock); + spin_lock_irqsave(&mhi_event->lock, flags); mhi_event->process_event(mhi_cntrl, mhi_event, U32_MAX); - spin_unlock_bh(&mhi_event->lock); + spin_unlock_irqrestore(&mhi_event->lock, flags); } void mhi_ctrl_ev_task(unsigned long data)
With spin_lock_bh(), it is possible that a tasklet processing data events gets pre-empted by RT tasks or a storm of threaded interrupt handlers ready to run on that core. While the tasklet gets scheduled out, it can hold the event ring spinlock and block another tasklet, for example, one processing an M0 state change event, from acquiring it. This can starve the core which blocks in an attempt to acquire the spinlock until it gets released. Fix the issue by disabling pre-emption on the core processing data events and allow the tasklet to run to completion such that other tasklets do not block on it for long periods. Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device") Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org> --- v2: -Updated description to clarify the scenario drivers/bus/mhi/core/main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)