Messages in this thread Patch in this message | | | From | Jia-Ju Bai <> | Subject | [PATCH] char: pcmcia: cm4000_cs: Replace mdelay with usleep_range in set_protocol | Date | Sun, 18 Mar 2018 22:49:57 +0800 |
| |
set_protocol() is never called in atomic context.
The call chains ending up at set_protocol() are: [1] set_protocol() <- monitor_card() [2] set_protocol() <- cmm_ioctl() monitor_card() is only set in setup_timer(), and cmm_ioctl() is only set as ".unlocked_ioctl" in file_operations structure "cm4000_fops".
Despite never getting called from atomic context, set_protocol() calls mdelay(10), i.e. busy wait for 10ms. That is not necessary and can be replaced with usleep_range to avoid busy waiting.
This is found by a static analysis tool named DCNS written by myself.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> --- drivers/char/pcmcia/cm4000_cs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/char/pcmcia/cm4000_cs.c b/drivers/char/pcmcia/cm4000_cs.c index cd53771..56fc671 100644 --- a/drivers/char/pcmcia/cm4000_cs.c +++ b/drivers/char/pcmcia/cm4000_cs.c @@ -530,7 +530,7 @@ static int set_protocol(struct cm4000_dev *dev, struct ptsreq *ptsreq) DEBUGP(5, dev, "NumRecBytes is valid\n"); break; } - mdelay(10); + usleep_range(10000, 11000); } if (i == 100) { DEBUGP(5, dev, "Timeout waiting for NumRecBytes getting " @@ -546,7 +546,7 @@ static int set_protocol(struct cm4000_dev *dev, struct ptsreq *ptsreq) DEBUGP(2, dev, "NumRecBytes = %i\n", num_bytes_read); break; } - mdelay(10); + usleep_range(10000, 11000); } /* check whether it is a short PTS reply? */ -- 1.9.1
| |