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Subjectdrivers/gpu/drm/nouveau/nouveau_dp.c:237 nouveau_dp_irq() warn: variable dereferenced before check 'outp' (see line 232)
tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 2258c2dc850b8605cb66b3383e50b9dddd1c6580
commit: 773eb04d14a11552b2c3953097ed09cde2ab4831 drm/nouveau/disp: expose conn event class
config: ia64-randconfig-m031-20221229
compiler: ia64-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>

smatch warnings:
drivers/gpu/drm/nouveau/nouveau_dp.c:237 nouveau_dp_irq() warn: variable dereferenced before check 'outp' (see line 232)

vim +/outp +237 drivers/gpu/drm/nouveau/nouveau_dp.c

773eb04d14a115 Ben Skeggs 2022-06-01 225 void
773eb04d14a115 Ben Skeggs 2022-06-01 226 nouveau_dp_irq(struct work_struct *work)
a0922278f83eae Lyude Paul 2020-08-26 227 {
773eb04d14a115 Ben Skeggs 2022-06-01 228 struct nouveau_connector *nv_connector =
773eb04d14a115 Ben Skeggs 2022-06-01 229 container_of(work, typeof(*nv_connector), irq_work);
a0922278f83eae Lyude Paul 2020-08-26 230 struct drm_connector *connector = &nv_connector->base;
a0922278f83eae Lyude Paul 2020-08-26 231 struct nouveau_encoder *outp = find_encoder(connector, DCB_OUTPUT_DP);
773eb04d14a115 Ben Skeggs 2022-06-01 @232 struct nouveau_drm *drm = nouveau_drm(outp->base.base.dev);
^^^^^^
Dereference.

a0922278f83eae Lyude Paul 2020-08-26 233 struct nv50_mstm *mstm;
016dacb60e6d4b Ben Skeggs 2022-06-01 234 u64 hpd = 0;
a4efad354cf1b9 Lyude Paul 2020-08-26 235 int ret;
a0922278f83eae Lyude Paul 2020-08-26 236
a0922278f83eae Lyude Paul 2020-08-26 @237 if (!outp)
^^^^
Checked too late.

a0922278f83eae Lyude Paul 2020-08-26 238 return;
a0922278f83eae Lyude Paul 2020-08-26 239
a0922278f83eae Lyude Paul 2020-08-26 240 mstm = outp->dp.mstm;
a0922278f83eae Lyude Paul 2020-08-26 241 NV_DEBUG(drm, "service %s\n", connector->name);
a0922278f83eae Lyude Paul 2020-08-26 242
a0922278f83eae Lyude Paul 2020-08-26 243 mutex_lock(&outp->dp.hpd_irq_lock);
a0922278f83eae Lyude Paul 2020-08-26 244
a0922278f83eae Lyude Paul 2020-08-26 245 if (mstm && mstm->is_mst) {
a0922278f83eae Lyude Paul 2020-08-26 246 if (!nv50_mstm_service(drm, nv_connector, mstm))
773eb04d14a115 Ben Skeggs 2022-06-01 247 hpd |= NVIF_CONN_EVENT_V0_UNPLUG;
a0922278f83eae Lyude Paul 2020-08-26 248 } else {
a0922278f83eae Lyude Paul 2020-08-26 249 drm_dp_cec_irq(&nv_connector->aux);
a4efad354cf1b9 Lyude Paul 2020-08-26 250
a4efad354cf1b9 Lyude Paul 2020-08-26 251 if (nouveau_dp_has_sink_count(connector, outp)) {
a4efad354cf1b9 Lyude Paul 2020-08-26 252 ret = drm_dp_read_sink_count(&nv_connector->aux);
a4efad354cf1b9 Lyude Paul 2020-08-26 253 if (ret != outp->dp.sink_count)
773eb04d14a115 Ben Skeggs 2022-06-01 254 hpd |= NVIF_CONN_EVENT_V0_PLUG;
a4efad354cf1b9 Lyude Paul 2020-08-26 255 if (ret >= 0)
a4efad354cf1b9 Lyude Paul 2020-08-26 256 outp->dp.sink_count = ret;
a4efad354cf1b9 Lyude Paul 2020-08-26 257 }
a0922278f83eae Lyude Paul 2020-08-26 258 }
a0922278f83eae Lyude Paul 2020-08-26 259
a0922278f83eae Lyude Paul 2020-08-26 260 mutex_unlock(&outp->dp.hpd_irq_lock);
a4efad354cf1b9 Lyude Paul 2020-08-26 261
773eb04d14a115 Ben Skeggs 2022-06-01 262 nouveau_connector_hpd(nv_connector, NVIF_CONN_EVENT_V0_IRQ | hpd);
a0922278f83eae Lyude Paul 2020-08-26 263 }

--
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https://01.org/lkp

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