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Date: Mon, 1 Oct 2018 17:22:22 +0200
From: Ursula Braun <ubraun@...ux.ibm.com>
To: Dan Carpenter <dan.carpenter@...cle.com>, kbuild@...org
Cc: kbuild-all@...org, davem@...emloft.net, netdev@...r.kernel.org,
linux-s390@...r.kernel.org, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com, raspl@...ux.ibm.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 2/5] net/smc: remove duplicate mutex_unlock
On 09/20/2018 11:12 AM, Dan Carpenter wrote:
> Hi Ursula,
>
> I love your patch! Perhaps something to improve:
>
> [auto build test WARNING on net/master]
>
> url: https://github.com/0day-ci/linux/commits/Ursula-Braun/net-smc-fixes-2018-09-18/20180919-080857
>
> smatch warnings:
> net/smc/af_smc.c:1289 smc_listen_work() warn: inconsistent returns 'mutex:&smc_create_lgr_pending'.
> Locked on: line 1285
> Unlocked on: line 1209
>
> # https://github.com/0day-ci/linux/commit/c69342ef9becfe90f3778db1c386abdd80b786d1
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout c69342ef9becfe90f3778db1c386abdd80b786d1
> vim +1289 net/smc/af_smc.c
>
> 3b2dec260 Hans Wippel 2018-05-18 1231 /* IPSec connections opt out of SMC-R optimizations */
> 3b2dec260 Hans Wippel 2018-05-18 1232 if (using_ipsec(new_smc)) {
> 3b2dec260 Hans Wippel 2018-05-18 1233 smc_listen_decline(new_smc, SMC_CLC_DECL_IPSEC, 0);
> 3b2dec260 Hans Wippel 2018-05-18 1234 return;
> 3b2dec260 Hans Wippel 2018-05-18 1235 }
> 3b2dec260 Hans Wippel 2018-05-18 1236
> 3b2dec260 Hans Wippel 2018-05-18 1237 mutex_lock(&smc_create_lgr_pending);
> 3b2dec260 Hans Wippel 2018-05-18 1238 smc_close_init(new_smc);
> 3b2dec260 Hans Wippel 2018-05-18 1239 smc_rx_init(new_smc);
> 3b2dec260 Hans Wippel 2018-05-18 1240 smc_tx_init(new_smc);
> 3b2dec260 Hans Wippel 2018-05-18 1241
> 413498440 Hans Wippel 2018-06-28 1242 /* check if ISM is available */
> 413498440 Hans Wippel 2018-06-28 1243 if ((pclc->hdr.path == SMC_TYPE_D || pclc->hdr.path == SMC_TYPE_B) &&
> 413498440 Hans Wippel 2018-06-28 1244 !smc_check_ism(new_smc, &ismdev) &&
> 413498440 Hans Wippel 2018-06-28 1245 !smc_listen_ism_init(new_smc, pclc, ismdev, &local_contact)) {
> 413498440 Hans Wippel 2018-06-28 1246 ism_supported = true;
> 413498440 Hans Wippel 2018-06-28 1247 }
> 413498440 Hans Wippel 2018-06-28 1248
> 3b2dec260 Hans Wippel 2018-05-18 1249 /* check if RDMA is available */
> 413498440 Hans Wippel 2018-06-28 1250 if (!ism_supported &&
> 413498440 Hans Wippel 2018-06-28 1251 ((pclc->hdr.path != SMC_TYPE_R && pclc->hdr.path != SMC_TYPE_B) ||
> 7005ada68 Ursula Braun 2018-07-25 1252 smc_vlan_by_tcpsk(new_smc->clcsock, &vlan) ||
> 7005ada68 Ursula Braun 2018-07-25 1253 smc_check_rdma(new_smc, &ibdev, &ibport, vlan, NULL) ||
> 3b2dec260 Hans Wippel 2018-05-18 1254 smc_listen_rdma_check(new_smc, pclc) ||
> 3b2dec260 Hans Wippel 2018-05-18 1255 smc_listen_rdma_init(new_smc, pclc, ibdev, ibport,
> 3b2dec260 Hans Wippel 2018-05-18 1256 &local_contact) ||
> 413498440 Hans Wippel 2018-06-28 1257 smc_listen_rdma_reg(new_smc, local_contact))) {
> 3b2dec260 Hans Wippel 2018-05-18 1258 /* SMC not supported, decline */
> 145686baa Ursula Braun 2017-10-25 1259 mutex_unlock(&smc_create_lgr_pending);
> 603cc1498 Karsten Graul 2018-07-25 1260 smc_listen_decline(new_smc, SMC_CLC_DECL_MODEUNSUPP,
> 603cc1498 Karsten Graul 2018-07-25 1261 local_contact);
> 3b2dec260 Hans Wippel 2018-05-18 1262 return;
> a046d57da Ursula Braun 2017-01-09 1263 }
> a046d57da Ursula Braun 2017-01-09 1264
> 3b2dec260 Hans Wippel 2018-05-18 1265 /* send SMC Accept CLC message */
> 3b2dec260 Hans Wippel 2018-05-18 1266 rc = smc_clc_send_accept(new_smc, local_contact);
> 3b2dec260 Hans Wippel 2018-05-18 1267 if (rc) {
> 145686baa Ursula Braun 2017-10-25 1268 mutex_unlock(&smc_create_lgr_pending);
> 3b2dec260 Hans Wippel 2018-05-18 1269 smc_listen_decline(new_smc, rc, local_contact);
> 3b2dec260 Hans Wippel 2018-05-18 1270 return;
> 3b2dec260 Hans Wippel 2018-05-18 1271 }
> 3b2dec260 Hans Wippel 2018-05-18 1272
> 3b2dec260 Hans Wippel 2018-05-18 1273 /* receive SMC Confirm CLC message */
> 3b2dec260 Hans Wippel 2018-05-18 1274 reason_code = smc_clc_wait_msg(new_smc, &cclc, sizeof(cclc),
> 3b2dec260 Hans Wippel 2018-05-18 1275 SMC_CLC_CONFIRM);
> 3b2dec260 Hans Wippel 2018-05-18 1276 if (reason_code) {
> 3b2dec260 Hans Wippel 2018-05-18 1277 mutex_unlock(&smc_create_lgr_pending);
> 3b2dec260 Hans Wippel 2018-05-18 1278 smc_listen_decline(new_smc, reason_code, local_contact);
> 3b2dec260 Hans Wippel 2018-05-18 1279 return;
> 3b2dec260 Hans Wippel 2018-05-18 1280 }
> 3b2dec260 Hans Wippel 2018-05-18 1281
> 3b2dec260 Hans Wippel 2018-05-18 1282 /* finish worker */
> c69342ef9 Ursula Braun 2018-09-18 1283 if (!ism_supported) {
> c69342ef9 Ursula Braun 2018-09-18 1284 if (smc_listen_rdma_finish(new_smc, &cclc, local_contact))
> c69342ef9 Ursula Braun 2018-09-18 1285 return;
> ^^^^^^
> We need to mutex_unlock(&smc_create_lgr_pending); before the return.
>
The smatch warning is not necessary, since the mutex_unlock(&smc_create_lgr_pending)
for this case is done within smc_listen_rdma_finish().
> c69342ef9 Ursula Braun 2018-09-18 1286 }
> 3b2dec260 Hans Wippel 2018-05-18 1287 smc_conn_save_peer_info(new_smc, &cclc);
> 3b2dec260 Hans Wippel 2018-05-18 1288 mutex_unlock(&smc_create_lgr_pending);
> 3b2dec260 Hans Wippel 2018-05-18 @1289 smc_listen_out_connected(new_smc);
> a046d57da Ursula Braun 2017-01-09 1290 }
> a046d57da Ursula Braun 2017-01-09 1291
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation
>
But you could argue the code confuses smatch and other readers. Thus I could improve
readability with a patch like this:
---
net/smc/af_smc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1184,7 +1184,6 @@ static int smc_listen_rdma_finish(struct
return 0;
decline:
- mutex_unlock(&smc_create_lgr_pending);
smc_listen_decline(new_smc, reason_code, local_contact);
return reason_code;
}
@@ -1284,8 +1283,10 @@ static void smc_listen_work(struct work_
/* finish worker */
if (!ism_supported) {
- if (smc_listen_rdma_finish(new_smc, &cclc, local_contact))
+ if (smc_listen_rdma_finish(new_smc, &cclc, local_contact)) {
+ mutex_unlock(&smc_create_lgr_pending);
return;
+ }
}
smc_conn_save_peer_info(new_smc, &cclc);
mutex_unlock(&smc_create_lgr_pending);
---
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