From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6FCC19DFA5 for ; Sat, 15 Feb 2025 09:28:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739611696; cv=none; b=d1NVRkHMpxQng6KL5r7oOOs8dOSaDnsdYO6DxG0i+0JaX9NBYgF0v9BDq9MDufpvH2vTTXCcm54mkkaqtSxSbevWcmjL/W+AvhDnEwpYDYdI/2PpTtqyMTk4jCoTvgkDHFNv7dbws1lHridAbmwIrtsx+E8afb9pHqiENqqWm/A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739611696; c=relaxed/simple; bh=QQjpX9+xUBD8RzBv+J9lE4D/BHtPWo4D4U8SL3B1WUg=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=a6sf8T6N8JrYXLTPOnwrn7I+fQjGHlpiyXGrPdH1mpEGPJWxK6N/hTI7/udqbsAbEf0BWzclGSuzIe8UIREinJefF0pES//ZDikKmzayuFmjwwHw/9IOl64bVE0GFYbcLd2yBfXcSBm1iWv7ro+XqtnZHgKC9LvmTYsjQhKXmVI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=YYpbbd6b; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="YYpbbd6b" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1739611692; bh=QQjpX9+xUBD8RzBv+J9lE4D/BHtPWo4D4U8SL3B1WUg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=YYpbbd6bVioKUx+jdEIEHKG2/pqedC6pc8dAI1ibk0/aiqRuRXMZt5OWqr5H1O5FH 7mq+55uDiBl2KRSVka2ppRWu5U58/p14rPbcevbABW9wOvI0/5l/VeoxBhCu1bL9vK kmwTwau8B1ucAguF/sBuluzmyPLKkmc5TUv0IYK1uuP3RizFmV5yumkXHBp8nCPNtI hPivHIQXtkRKgHZIIlvvD0bW9kJ6tzu7hmNtO8Y7dwIVjSpPJvCny5yZMARiWPQKTi Nf9uPBvyr/I467IE7szIWvK6OYsr8jCqlKaeVMGnOASLMB7gqYWJOG/5df2MI4VXEG XCbTiQjbegelw== Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 38ECA17E0657; Sat, 15 Feb 2025 10:28:12 +0100 (CET) Date: Sat, 15 Feb 2025 10:28:07 +0100 From: Boris Brezillon To: =?UTF-8?B?QWRyacOhbg==?= Larumbe Cc: Steven Price , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , kernel@collabora.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] drm/panthor: Replace sleep locks with spinlocks in fdinfo path Message-ID: <20250215102807.7502e7ba@collabora.com> In-Reply-To: <20250214210009.1994543-1-adrian.larumbe@collabora.com> References: <20250214210009.1994543-1-adrian.larumbe@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Fri, 14 Feb 2025 20:55:20 +0000 Adri=C3=A1n Larumbe wrote: > Commit 0590c94c3596 ("drm/panthor: Fix race condition when gathering fdin= fo > group samples") introduced an xarray lock to deal with potential > use-after-free errors when accessing groups fdinfo figures. However, this > toggles the kernel's atomic context status, so the next nested mutex lock > will raise a warning when the kernel is compiled with mutex debug options: >=20 > CONFIG_DEBUG_RT_MUTEXES=3Dy > CONFIG_DEBUG_MUTEXES=3Dy >=20 > Replace Panthor's group fdinfo data mutex with a guarded spinlock. >=20 > Signed-off-by: Adri=C3=A1n Larumbe > 0590c94c3596 ("drm/panthor: Fix race condition when gathering fdinfo grou= p samples") My previous Reviewed-by: Boris Brezillon stands. > --- > drivers/gpu/drm/panthor/panthor_sched.c | 26 ++++++++++++------------- > 1 file changed, 12 insertions(+), 14 deletions(-) >=20 > diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/pa= nthor/panthor_sched.c > index 1a276db095ff..4d31d1967716 100644 > --- a/drivers/gpu/drm/panthor/panthor_sched.c > +++ b/drivers/gpu/drm/panthor/panthor_sched.c > @@ -9,6 +9,7 @@ > #include > =20 > #include > +#include > #include > #include > #include > @@ -631,10 +632,10 @@ struct panthor_group { > struct panthor_gpu_usage data; > =20 > /** > - * @lock: Mutex to govern concurrent access from drm file's fdinfo cal= lback > - * and job post-completion processing function > + * @fdinfo.lock: Spinlock to govern concurrent access from drm file's = fdinfo > + * callback and job post-completion processing function > */ > - struct mutex lock; > + spinlock_t lock; > =20 > /** @fdinfo.kbo_sizes: Aggregate size of private kernel BO's held by t= he group. */ > size_t kbo_sizes; > @@ -910,8 +911,6 @@ static void group_release_work(struct work_struct *wo= rk) > release_work); > u32 i; > =20 > - mutex_destroy(&group->fdinfo.lock); > - > for (i =3D 0; i < group->queue_count; i++) > group_free_queue(group, group->queues[i]); > =20 > @@ -2861,12 +2860,12 @@ static void update_fdinfo_stats(struct panthor_jo= b *job) > struct panthor_job_profiling_data *slots =3D queue->profiling.slots->km= ap; > struct panthor_job_profiling_data *data =3D &slots[job->profiling.slot]; > =20 > - mutex_lock(&group->fdinfo.lock); > - if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_CYCLES) > - fdinfo->cycles +=3D data->cycles.after - data->cycles.before; > - if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_TIMESTAMP) > - fdinfo->time +=3D data->time.after - data->time.before; > - mutex_unlock(&group->fdinfo.lock); > + scoped_guard(spinlock, &group->fdinfo.lock) { > + if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_CYCLES) > + fdinfo->cycles +=3D data->cycles.after - data->cycles.before; > + if (job->profiling.mask & PANTHOR_DEVICE_PROFILING_TIMESTAMP) > + fdinfo->time +=3D data->time.after - data->time.before; > + } > } > =20 > void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile) > @@ -2880,12 +2879,11 @@ void panthor_fdinfo_gather_group_samples(struct p= anthor_file *pfile) > =20 > xa_lock(&gpool->xa); > xa_for_each(&gpool->xa, i, group) { > - mutex_lock(&group->fdinfo.lock); > + guard(spinlock)(&group->fdinfo.lock); > pfile->stats.cycles +=3D group->fdinfo.data.cycles; > pfile->stats.time +=3D group->fdinfo.data.time; > group->fdinfo.data.cycles =3D 0; > group->fdinfo.data.time =3D 0; > - mutex_unlock(&group->fdinfo.lock); > } > xa_unlock(&gpool->xa); > } > @@ -3537,7 +3535,7 @@ int panthor_group_create(struct panthor_file *pfile, > mutex_unlock(&sched->reset.lock); > =20 > add_group_kbo_sizes(group->ptdev, group); > - mutex_init(&group->fdinfo.lock); > + spin_lock_init(&group->fdinfo.lock); > =20 > return gid; > =20