Re: [PATCH v3 2/2] fsi: sbefifo: Handle pending write command

From: Eddie James
Date: Wed Oct 11 2023 - 15:22:00 EST



On 10/10/23 15:43, Ninad Palsule wrote:
If previous write command is still pending then free it first.

As per the current kernel driver design, write operation prepares a
buffer for FSI write, the actual FSI write is performed on next read
operation. There is a possibility of memory leak if buggy application
sends two back to back writes or two parallel writes.


Reviewed-by: Eddie James <eajames@xxxxxxxxxxxxx>



Signed-off-by: Ninad Palsule <ninad@xxxxxxxxxxxxx>
---
v3:
- Incorporated review comments by Eddie.
---
drivers/fsi/fsi-sbefifo.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
index a95b32461f8f3..1cc88a78e588a 100644
--- a/drivers/fsi/fsi-sbefifo.c
+++ b/drivers/fsi/fsi-sbefifo.c
@@ -877,6 +877,13 @@ static ssize_t sbefifo_user_write(struct file *file, const char __user *buf,
mutex_lock(&user->file_lock);
+ /* If previous write command is still pending then free it. It is safe
+ * to do that because read cannot be in progress since we hold the
+ * lock.
+ */
+ if (user->pending_cmd)
+ sbefifo_release_command(user);
+
/* Can we use the pre-allocate buffer ? If not, allocate */
if (len <= PAGE_SIZE)
user->pending_cmd = user->cmd_page;