[PATCH 2/3] Make res_init() thread safe.
Bernhard Reutner-Fischer
rep.dot.nop at gmail.com
Tue Nov 12 15:18:24 UTC 2013
On Thu, Apr 11, 2013 at 06:51:36AM +0000, Sørensen, Kenneth wrote:
>
> From c34c95553ac7ebd278059fada06319aaf132c906 Mon Sep 17 00:00:00 2001
> From: Kenneth Soerensen <kenneth.sorensen at spectralink.com>
> Date: Wed, 10 Apr 2013 16:52:52 +0200
> Subject: [PATCH 2/3] Make res_init() thread safe.
>
> res_init() was not atomic, which could give undesired behaviour. Now
> res_init() is completely locked under one lock and the locking is
> removed from __res_vinit().
>
> Signed-off-by: Kenneth Soerensen <kenneth.sorensen at spectralink.com>
> ---
> libc/inet/resolv.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
> index df6fefd..c230534 100644
> --- a/libc/inet/resolv.c
> +++ b/libc/inet/resolv.c
> @@ -3434,7 +3434,6 @@ __res_vinit(res_state rp, int preinit)
> int m = 0;
> #endif
>
> - __UCLIBC_MUTEX_LOCK(__resolv_lock);
> __close_nameservers();
> __open_nameservers();
>
> @@ -3526,7 +3525,6 @@ __res_vinit(res_state rp, int preinit)
>
> rp->options |= RES_INIT;
>
> - __UCLIBC_MUTEX_UNLOCK(__resolv_lock);
> return 0;
> }
>
> @@ -3576,11 +3574,11 @@ res_init(void)
> if (!_res.id)
> _res.id = res_randomid();
>
> - __UCLIBC_MUTEX_UNLOCK(__resolv_lock);
> -
> __res_vinit(&_res, 1);
> __res_sync = res_sync_func;
>
> + __UCLIBC_MUTEX_UNLOCK(__resolv_lock);
> +
> return 0;
> }
> libc_hidden_def(res_init)
> @@ -3679,7 +3677,9 @@ struct __res_state *__resp = &_res;
> int
> res_ninit(res_state statp)
> {
> + __UCLIBC_MUTEX_LOCK(__resolv_lock);
> return __res_vinit(statp, 0);
> + __UCLIBC_MUTEX_UNLOCK(__resolv_lock);
This hunk had the locking wrong as you can see. Applied with slight
adjustment.
Thanks,
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