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Date: Wed, 27 Dec 2023 21:56:46 +0100 (CET)
From: Julia Lawall <julia.lawall@inria.fr>
To: Ben Skeggs <bskeggs@redhat.com>, Lyude Paul <lyude@redhat.com>
cc: linux-kernel@vger.kernel.org, oe-kbuild-all@lists.linux.dev
Subject: drivers/gpu/drm/nouveau/nvkm/engine/fifo/chan.c:258:2-8: preceding
 lock on line 251 (fwd)
Message-ID: <alpine.DEB.2.22.394.2312272155490.3107@hadrien>
User-Agent: Alpine 2.22 (DEB 394 2020-01-19)
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Hello,

There is no bug here, but it could be nice to refer to the lock in the
same way at all call sites (see line 258.

julia

---------- Forwarded message ----------
Date: Wed, 27 Dec 2023 22:34:45 +0800
From: kernel test robot <lkp@intel.com>
To: oe-kbuild@lists.linux.dev
Cc: lkp@intel.com, Julia Lawall <julia.lawall@inria.fr>
Subject: drivers/gpu/drm/nouveau/nvkm/engine/fifo/chan.c:258:2-8: preceding lock
     on line 251

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
CC: linux-kernel@vger.kernel.org
TO: Ben Skeggs <bskeggs@redhat.com>
CC: Lyude Paul <lyude@redhat.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   fbafc3e621c3f4ded43720fdb1d6ce1728ec664e
commit: f48dd2936138882d7755cbbc5d9984015c75980c drm/nouveau/fifo: add new engine context tracking
date:   1 year, 2 months ago
:::::: branch date: 2 days ago
:::::: commit date: 1 year, 2 months ago
config: loongarch-randconfig-r062-20231222 (https://download.01.org/0day-ci/archive/20231227/202312272217.k0uoS8R5-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 13.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Julia Lawall <julia.lawall@inria.fr>
| Closes: https://lore.kernel.org/r/202312272217.k0uoS8R5-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/gpu/drm/nouveau/nvkm/engine/fifo/chan.c:258:2-8: preceding lock on line 251

vim +258 drivers/gpu/drm/nouveau/nvkm/engine/fifo/chan.c

f48dd293613888 Ben Skeggs 2022-06-01  240
f48dd293613888 Ben Skeggs 2022-06-01  241  int
f48dd293613888 Ben Skeggs 2022-06-01  242  nvkm_chan_cctx_get(struct nvkm_chan *chan, struct nvkm_engn *engn, struct nvkm_cctx **pcctx,
f48dd293613888 Ben Skeggs 2022-06-01  243  		   struct nvkm_client *client)
f48dd293613888 Ben Skeggs 2022-06-01  244  {
f48dd293613888 Ben Skeggs 2022-06-01  245  	struct nvkm_cgrp *cgrp = chan->cgrp;
f48dd293613888 Ben Skeggs 2022-06-01  246  	struct nvkm_vctx *vctx;
f48dd293613888 Ben Skeggs 2022-06-01  247  	struct nvkm_cctx *cctx;
f48dd293613888 Ben Skeggs 2022-06-01  248  	int ret;
f48dd293613888 Ben Skeggs 2022-06-01  249
f48dd293613888 Ben Skeggs 2022-06-01  250  	/* Look for an existing channel context for this engine+VEID. */
f48dd293613888 Ben Skeggs 2022-06-01 @251  	mutex_lock(&cgrp->mutex);
f48dd293613888 Ben Skeggs 2022-06-01  252  	cctx = nvkm_list_find(cctx, &chan->cctxs, head,
f48dd293613888 Ben Skeggs 2022-06-01  253  			      cctx->vctx->ectx->engn == engn && cctx->vctx->vmm == chan->vmm);
f48dd293613888 Ben Skeggs 2022-06-01  254  	if (cctx) {
f48dd293613888 Ben Skeggs 2022-06-01  255  		refcount_inc(&cctx->refs);
f48dd293613888 Ben Skeggs 2022-06-01  256  		*pcctx = cctx;
f48dd293613888 Ben Skeggs 2022-06-01  257  		mutex_unlock(&chan->cgrp->mutex);
f48dd293613888 Ben Skeggs 2022-06-01 @258  		return 0;
f48dd293613888 Ben Skeggs 2022-06-01  259  	}
f48dd293613888 Ben Skeggs 2022-06-01  260
f48dd293613888 Ben Skeggs 2022-06-01  261  	/* Nope - create a fresh one.  But, sub-context first. */
f48dd293613888 Ben Skeggs 2022-06-01  262  	ret = nvkm_cgrp_vctx_get(cgrp, engn, chan, &vctx, client);
f48dd293613888 Ben Skeggs 2022-06-01  263  	if (ret) {
f48dd293613888 Ben Skeggs 2022-06-01  264  		CHAN_ERROR(chan, "vctx %d[%s]: %d", engn->id, engn->engine->subdev.name, ret);
f48dd293613888 Ben Skeggs 2022-06-01  265  		goto done;
f48dd293613888 Ben Skeggs 2022-06-01  266  	}
f48dd293613888 Ben Skeggs 2022-06-01  267
f48dd293613888 Ben Skeggs 2022-06-01  268  	/* Now, create the channel context - to track engine binding. */
f48dd293613888 Ben Skeggs 2022-06-01  269  	CHAN_TRACE(chan, "ctor cctx %d[%s]", engn->id, engn->engine->subdev.name);
f48dd293613888 Ben Skeggs 2022-06-01  270  	if (!(cctx = *pcctx = kzalloc(sizeof(*cctx), GFP_KERNEL))) {
f48dd293613888 Ben Skeggs 2022-06-01  271  		nvkm_cgrp_vctx_put(cgrp, &vctx);
f48dd293613888 Ben Skeggs 2022-06-01  272  		ret = -ENOMEM;
f48dd293613888 Ben Skeggs 2022-06-01  273  		goto done;
f48dd293613888 Ben Skeggs 2022-06-01  274  	}
f48dd293613888 Ben Skeggs 2022-06-01  275
f48dd293613888 Ben Skeggs 2022-06-01  276  	cctx->vctx = vctx;
f48dd293613888 Ben Skeggs 2022-06-01  277  	refcount_set(&cctx->refs, 1);
f48dd293613888 Ben Skeggs 2022-06-01  278  	refcount_set(&cctx->uses, 0);
f48dd293613888 Ben Skeggs 2022-06-01  279  	list_add_tail(&cctx->head, &chan->cctxs);
f48dd293613888 Ben Skeggs 2022-06-01  280  done:
f48dd293613888 Ben Skeggs 2022-06-01  281  	mutex_unlock(&cgrp->mutex);
f48dd293613888 Ben Skeggs 2022-06-01  282  	return ret;
f48dd293613888 Ben Skeggs 2022-06-01  283  }
f48dd293613888 Ben Skeggs 2022-06-01  284

-- 
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