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Merge branch 'bugfix/vfs_sock_select_race_v4.4' into 'release/v4.4'

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vfs: Fix potential select() race if both sock and other-fd trigger (v4.4)

See merge request espressif/esp-idf!18175
This commit is contained in:
David Čermák 2022-05-20 12:55:09 +08:00
commit db98a4b2ef
1 changed files with 10 additions and 2 deletions
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12
components/vfs/vfs.c
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@ -1053,8 +1053,16 @@ int esp_vfs_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds
if (ret >= 0) {
ret += set_global_fd_sets(vfs_fds_triple, vfs_count, readfds, writefds, errorfds);
}
if (sel_sem.is_sem_local && sel_sem.sem) {
vSemaphoreDelete(sel_sem.sem);
if (sel_sem.sem) { // Cleanup the select semaphore
if (sel_sem.is_sem_local) {
vSemaphoreDelete(sel_sem.sem);
} else if (socket_select) {
SemaphoreHandle_t *s = sel_sem.sem;
/* Select might have been triggered from both lwip and vfs fds at the same time, and
* we have to make sure that the lwip semaphore is cleared when we exit select().
* It is safe, as the semaphore belongs to the calling thread. */
xSemaphoreTake(*s, 0);
}
sel_sem.sem = NULL;
}
_lock_acquire(&s_fd_table_lock);