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libc/netdb: Support the recursive lock

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Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao 2022-04-01 12:26:30 +08:00 committed by Masayuki Ishikawa
parent 9f7ecbd5b7
commit a8cac59864
1 changed files with 25 additions and 2 deletions
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27
libs/libc/netdb/lib_dnsinit.c
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@ -30,6 +30,7 @@
#include <arpa/inet.h>
#include <nuttx/sched.h>
#include <nuttx/semaphore.h>
#include "netdb/lib_dns.h"
@ -40,7 +41,9 @@
/* Protects DNS cache, nameserver list and notify list. */
static sem_t g_dns_sem = SEM_INITIALIZER(1);
static sem_t g_dns_sem = SEM_INITIALIZER(1);
static pid_t g_dns_holder = INVALID_PROCESS_ID;
static int g_dns_count;
/****************************************************************************
* Public Data
@ -143,9 +146,20 @@ bool dns_initialize(void)
void dns_semtake(void)
{
pid_t me = getpid();
int errcode = 0;
int ret;
/* Does this thread already hold the semaphore? */
if (g_dns_holder == me)
{
/* Yes.. just increment the reference count */
g_dns_count++;
return;
}
do
{
ret = _SEM_WAIT(&g_dns_sem);
@ -156,6 +170,9 @@ void dns_semtake(void)
}
}
while (ret < 0 && errcode == EINTR);
g_dns_holder = me;
g_dns_count = 1;
}
/****************************************************************************
@ -168,5 +185,11 @@ void dns_semtake(void)
void dns_semgive(void)
{
DEBUGVERIFY(_SEM_POST(&g_dns_sem));
DEBUGASSERT(g_dns_holder == getpid() && g_dns_count > 0);
if (--g_dns_count == 0)
{
g_dns_holder = INVALID_PROCESS_ID;
DEBUGVERIFY(_SEM_POST(&g_dns_sem));
}
}