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task: assign_pid retry after malloc

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Calling malloc in the critical section may cause thread switching.
Add a retry mechanism to handle the situation where other threads have been successfully expanded.

Signed-off-by: yinshengkai <yinshengkai@xiaomi.com>
Signed-off-by: ligd <liguiding1@xiaomi.com>
This commit is contained in:
yinshengkai 2024-02-04 20:19:43 +08:00 committed by Alan C. Assis
parent 8b13572d64
commit baf79de7e5
1 changed files with 35 additions and 7 deletions
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42
sched/task/task_setup.c
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@ -82,6 +82,7 @@ static const char g_noname[] = "<noname>";
static int nxtask_assign_pid(FAR struct tcb_s *tcb)
{
FAR struct tcb_s **pidhash;
irqstate_t flags;
pid_t next_pid;
int hash_ndx;
void *temp;
@ -92,15 +93,15 @@ static int nxtask_assign_pid(FAR struct tcb_s *tcb)
* We cannot allow another task to be started.
*/
/* We'll try every allowable pid */
retry:
/* Protect the following operation with a critical section
* because g_pidhash is accessed from an interrupt context
*/
irqstate_t flags = enter_critical_section();
/* We'll try every allowable pid */
retry:
flags = enter_critical_section();
/* Get the next process ID candidate */
@ -140,13 +141,30 @@ retry:
* expand space.
*/
temp = g_pidhash;
/* Calling malloc in a critical section may cause thread switching.
* Here we check whether other threads have applied successfully,
* and if successful, return directly
*/
leave_critical_section(flags);
pidhash = kmm_zalloc(g_npidhash * 2 * sizeof(*pidhash));
if (pidhash == NULL)
{
leave_critical_section(flags);
return -ENOMEM;
}
/* Handle conner case: context siwtch happened when kmm_malloc */
flags = enter_critical_section();
if (temp != g_pidhash)
{
leave_critical_section(flags);
kmm_free(pidhash);
goto retry;
}
g_npidhash *= 2;
/* All original pid and hash_ndx are mismatch,
@ -155,6 +173,16 @@ retry:
for (i = 0; i < g_npidhash / 2; i++)
{
if (g_pidhash[i] == NULL)
{
/* If the pid is not used, skip it.
* This may be triggered when a context switch occurs
* during zalloc and a thread is destroyed.
*/
continue;
}
hash_ndx = PIDHASH(g_pidhash[i]->pid);
DEBUGASSERT(pidhash[hash_ndx] == NULL);
pidhash[hash_ndx] = g_pidhash[i];
@ -162,8 +190,8 @@ retry:
/* Release resource for original g_pidhash, using new g_pidhash */
temp = g_pidhash;
g_pidhash = pidhash;
leave_critical_section(flags);
kmm_free(temp);
/* Let's try every allowable pid again */