2018-04-10 12:41:34

by Jia-Ju Bai

Subject: [PATCH 1/2] scsi: st: Replace GFP_ATOMIC with GFP_KERNEL in st_probe

st_probe() is never called in atomic context.

st_probe() is only set as ".probe" in struct scsi_driver.

Despite never getting called from atomic context,
st_probe() calls kzalloc() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/scsi/st.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 94e402e..1da42f3 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -4290,7 +4290,7 @@ static int st_probe(struct device *dev)
goto out_buffer_free;
}

- tpnt = kzalloc(sizeof(struct scsi_tape), GFP_ATOMIC);
+ tpnt = kzalloc(sizeof(struct scsi_tape), GFP_KERNEL);
if (tpnt == NULL) {
sdev_printk(KERN_ERR, SDp,
"st: Can't allocate device descriptor.\n");
--
1.9.1

2018-04-20 22:41:46

by Martin K. Petersen

Subject: Re: [PATCH 1/2] scsi: st: Replace GFP_ATOMIC with GFP_KERNEL in st_probe

Jia-Ju,

> st_probe() is never called in atomic context.

Applied patches 1 and 2 to 4.18/scsi-queue. Thanks!

--
Martin K. Petersen Oracle Linux Engineering