From 993c1637a08f436eacc7b3f4eacbda8dac0b304b Mon Sep 17 00:00:00 2001 From: Christian Gromm Date: Tue, 8 May 2018 11:45:10 +0200 Subject: [PATCH] staging: most: cdev: fix race condition This patch fixes a race condition between the functions disconnect and poll. Signed-off-by: Christian Gromm Signed-off-by: Greg Kroah-Hartman --- drivers/staging/most/cdev/cdev.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/staging/most/cdev/cdev.c b/drivers/staging/most/cdev/cdev.c index 8e7652545402..4569838f27a0 100644 --- a/drivers/staging/most/cdev/cdev.c +++ b/drivers/staging/most/cdev/cdev.c @@ -292,13 +292,15 @@ static __poll_t comp_poll(struct file *filp, poll_table *wait) poll_wait(filp, &c->wq, wait); + mutex_lock(&c->io_mutex); if (c->cfg->direction == MOST_CH_RX) { - if (!kfifo_is_empty(&c->fifo)) + if (!c->dev || !kfifo_is_empty(&c->fifo)) mask |= EPOLLIN | EPOLLRDNORM; } else { - if (!kfifo_is_empty(&c->fifo) || ch_has_mbo(c)) + if (!c->dev || !kfifo_is_empty(&c->fifo) || ch_has_mbo(c)) mask |= EPOLLOUT | EPOLLWRNORM; } + mutex_unlock(&c->io_mutex); return mask; } -- 2.30.2