From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [46.235.227.194]) (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 E11B83173A for ; Thu, 25 Jan 2024 21:52:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.235.227.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706219546; cv=none; b=i1taoC4aEzIEGApIBljSq5nV1ZZyQg5dNLh7wM71WIqIFY6yKUn+ftTu2l6kM/DKpfJd5FaegChgbi4a8eC66H8761H82VTvbuSbkzx4NoaorsF6k0xewM/P65R6UrfPvbANTBVs3xHOjn5WPshazKE+4crvWfnUrMtWjH3kT3Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706219546; c=relaxed/simple; bh=HmHb/1j56mYypkJHtCxMuyE8iJQuLLhZ2r3pRbNJ0Ek=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=o7S9Yqqbu2NokAYvfWdWFz34tdOcSFViSsFqHVF9+17NpBdqhPpwfpFd3zV2jhc+pu60fDh8cn8eKt3BSajqzyEN55w13nyPxf9KSnu2+iG2PyI2iN4b9TClRvtaZstTt8BP75sB4Jz47LWf0sTcFqJDL489c9ARHj/D7jhKwqg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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=DjKPBOn5; arc=none smtp.client-ip=46.235.227.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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="DjKPBOn5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1706219543; bh=HmHb/1j56mYypkJHtCxMuyE8iJQuLLhZ2r3pRbNJ0Ek=; h=Date:Subject:To:References:From:In-Reply-To:From; b=DjKPBOn5DkLFgqwP0WrFz5zmWSBPLMUa00i2AzL5gujzFWsxBQJZtLk7yLL4Fk3mw qmf8pOZT2aIxEOOBFymm2cbk1Njwpow9/hYB9Dk8zf/mhLP307VzkWdqq4xBJF8wLf tlsvHel51nr4LS9KByd5zZvHCDSOwM61iCe7TAo8h0bWYUdSRNwZixl4i54JTwVIm6 yFQaOuEc9iAfV7ZRTQ4jdqHSm1HsPVgPgqP/FIYD2UOvIMWRoFH4wpvvrVhztuII52 DN7YkZbkTJfLwGjonrp80UCfEH/C+yzfA/rfDazDfJeZw/6PzT2FLOrO2Mlo4WEFVO a/Iznos2DQfjg== Received: from [100.109.49.129] (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madrid.collaboradmins.com (Postfix) with ESMTPSA id C958D37813DA; Thu, 25 Jan 2024 21:52:21 +0000 (UTC) Message-ID: Date: Fri, 26 Jan 2024 00:52:19 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v19 09/30] drm/shmem-helper: Add and use lockless drm_gem_shmem_get_pages() Content-Language: en-US To: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , =?UTF-8?Q?Christian_K=C3=B6nig?= , Qiang Yu , Steven Price , Boris Brezillon , Emma Anholt , Melissa Wen , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org References: <20240105184624.508603-1-dmitry.osipenko@collabora.com> <20240105184624.508603-10-dmitry.osipenko@collabora.com> From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/25/24 20:24, Daniel Vetter wrote: > On Fri, Jan 05, 2024 at 09:46:03PM +0300, Dmitry Osipenko wrote: >> Add lockless drm_gem_shmem_get_pages() helper that skips taking reservation >> lock if pages_use_count is non-zero, leveraging from atomicity of the >> refcount_t. Make drm_gem_shmem_mmap() to utilize the new helper. >> >> Acked-by: Maxime Ripard >> Reviewed-by: Boris Brezillon >> Suggested-by: Boris Brezillon >> Signed-off-by: Dmitry Osipenko >> --- >> drivers/gpu/drm/drm_gem_shmem_helper.c | 19 +++++++++++++++---- >> 1 file changed, 15 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c >> index cacf0f8c42e2..1c032513abf1 100644 >> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c >> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c >> @@ -226,6 +226,20 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) >> } >> EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); >> >> +static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem) >> +{ >> + int ret; > > Just random drive-by comment: a might_lock annotation here might be good, > or people could hit some really interesting bugs that are rather hard to > reproduce ... > -Sima Thanks for the suggestion! -- Best regards, Dmitry