Hi Steve, 1, from https://lore.kernel.org/lkml/31644881-134a-2d6e-dddf-e658a3a8176b@xxxxxxx/ I can see what your sent,I used a wrong email address,Now it correct. 2, > >Unless I'm mistaken the situation where some mappings may be NULL is > >caused by the loop in panfrost_lookup_bos() not completing > >successfully > >(panfrost_gem_mapping_get() returning NULL). In this case if > >mappings[i] > >is NULL then all following mappings must also be NULL. So 'break' > >allows > >us to skip the later ones. Admittedly the performance here isn't > >important so I'm not sure it's worth the optimisation, but AIUI this > >code isn't actually wrong. from panfrost_lookup_bos(),you can see: for (i = 0; i < job->bo_count; i++) { struct panfrost_gem_mapping *mapping; bo = to_panfrost_bo(job->bos[i]); ICUBE_DEBUG_PRINTK("panfrost bo gem handle=0x%x is_dumb=%d\n", bo->gem_handle, bo->is_dumb); if (!bo->is_dumb) { mapping = panfrost_gem_mapping_get(bo, priv); if (!mapping) { ret = -EINVAL; break; } atomic_inc(&bo->gpu_usecount); job->mappings[i] = mapping; } else { atomic_inc(&bo->gpu_usecount); job->mappings[i] = NULL; } } if bo->is_dumb is TRUE,the job->mappings[i] will set to NULL,and the while will be continue,so if job->mappings[i] is NULL,the following can not be NULL. 3, I've had this problem in our project,the value of is_dumb like these: 0 0 0 1 0 0 0 so,when job->mappings[i] is NULL,we can not break the while in panfrost_job_cleanup(). thanks Chunyou ÓÚ Fri, 18 Jun 2021 13:43:25 +0100 Steven Price <steven.price@xxxxxxx> дµÀ: > On 17/06/2021 09:04, ChunyouTang wrote: > > From: ChunyouTang <tangchunyou@xxxxxxxxxxxx> > > > > The 'break' can cause 'Memory manager not clean during takedown' > > > > It cannot use break to finish the circulation,it should use > > > > continue to traverse the circulation.it should put every mapping > > > > which is not NULL. > > You don't appear to have answered my question about whether you've > actually seen this happen (and ideally what circumstances). In my > previous email[1] I explained why I don't think this is needed. You > need to convince me that I've overlooked something. > > Thanks, > > Steve > > [1] > https://lore.kernel.org/r/31644881-134a-2d6e-dddf-e658a3a8176b%40arm.com > > > Signed-off-by: ChunyouTang <tangchunyou@xxxxxxxxxxxx> > > --- > > drivers/gpu/drm/panfrost/panfrost_job.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c > > b/drivers/gpu/drm/panfrost/panfrost_job.c index > > 6003cfeb1322..52bccc1d2d42 100644 --- > > a/drivers/gpu/drm/panfrost/panfrost_job.c +++ > > b/drivers/gpu/drm/panfrost/panfrost_job.c @@ -281,7 +281,7 @@ > > static void panfrost_job_cleanup(struct kref *ref) if > > (job->mappings) { for (i = 0; i < job->bo_count; i++) { > > if (!job->mappings[i]) > > - break; > > + continue; > > > > atomic_dec(&job->mappings[i]->obj->gpu_usecount); > > panfrost_gem_mapping_put(job->mappings[i]); > >
