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pty: use mutex to protect alloc minor

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If failed in pty_register2, it is possible to enter unregister_driver
function, which eventually calls ptmx_minor_free, resulting in mutex
conflict.

Signed-off-by: yangsong8 <yangsong8@xiaomi.com>
This commit is contained in:
yangsong8 2024-08-09 11:22:38 +08:00 committed by Xiang Xiao
parent 946ed96926
commit 6a38c37702
1 changed files with 4 additions and 11 deletions
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15
drivers/serial/ptmx.c
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@ -180,10 +180,10 @@ static int ptmx_open(FAR struct file *filep)
/* Allocate a PTY minor */
minor = ptmx_minor_allocate();
nxmutex_unlock(&g_ptmx.px_lock);
if (minor < 0)
{
ret = minor;
goto errout_with_lock;
return minor;
}
/* Create the master slave pair. This should create:
@ -197,7 +197,8 @@ static int ptmx_open(FAR struct file *filep)
ret = pty_register2(minor, true);
if (ret < 0)
{
goto errout_with_minor;
ptmx_minor_free(minor);
return ret;
}
/* Open the master device: /dev/ptyN, where N=minor */
@ -220,15 +221,7 @@ static int ptmx_open(FAR struct file *filep)
ret = unregister_driver(devname);
DEBUGASSERT(ret >= 0 || ret == -EBUSY); /* unregister_driver() should never fail */
nxmutex_unlock(&g_ptmx.px_lock);
return OK;
errout_with_minor:
ptmx_minor_free(minor);
errout_with_lock:
nxmutex_unlock(&g_ptmx.px_lock);
return ret;
}
/****************************************************************************