xiaoxiang781216 commented on a change in pull request #5204:
URL: https://github.com/apache/incubator-nuttx/pull/5204#discussion_r821634793
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File path: drivers/input/ajoystick.c
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@@ -526,12 +461,7 @@ static ssize_t ajoy_read(FAR struct file *filep, FAR char
*buffer,
/* Get exclusive access to the driver structure */
- ret = ajoy_takesem(&priv->au_exclsem);
- if (ret < 0)
- {
- ierr("ERROR: ajoy_takesem failed: %d\n", ret);
- return ret;
- }
+ flags = enter_critical_section();
Review comment:
You can't fix the race condition in all case. How to handle this
sequence?
1. Thread A just enter ajoy_close and switch to thread B
2. Thread B just enter ajoy_read and switch to thread A again
3. Thread A continue ajoy_close and release opriv
4. Thread B resume and touch the freed memory
Basically, the resource release is very very special, you can't protect the
resource by the normal approach.
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