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Tue, 25 Feb 2025 09:36:02 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 3umZAQKPvWceFwAAD6G6ig (envelope-from ); Tue, 25 Feb 2025 09:36:02 +0000 Date: Tue, 25 Feb 2025 10:36:01 +0100 Message-ID: <87zfia74e6.wl-tiwai@suse.de> From: Takashi Iwai To: Jani Nikula Cc: Dan Carpenter , Lukas Wunner , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Takashi Iwai , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Su Hui Subject: Re: [PATCH] vgaswitcheroo: Fix error checking in vga_switcheroo_register_audio_client() In-Reply-To: <87zfia5r0a.fsf@intel.com> References: <87eczn7adi.fsf@intel.com> <8e161bf8-70f6-4557-8fa8-81d4bbfab91f@stanley.mountain> <87zfia5r0a.fsf@intel.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 6533F1F44F X-Spam-Score: -3.51 X-Rspamd-Action: no action X-Spamd-Result: default: False [-3.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[13]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; FUZZY_BLOCKED(0.00)[rspamd.com]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linaro.org,wunner.de,linux.intel.com,kernel.org,suse.de,gmail.com,ffwll.ch,lists.freedesktop.org,vger.kernel.org,nfschina.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:dkim,linaro.org:email,nfschina.com:email]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spam-Level: On Tue, 25 Feb 2025 10:10:29 +0100, Jani Nikula wrote: > > On Mon, 24 Feb 2025, Dan Carpenter wrote: > > On Mon, Feb 24, 2025 at 03:14:33PM +0200, Jani Nikula wrote: > >> On Wed, 19 Feb 2025, Dan Carpenter wrote: > >> > The "id" variable is an enum and in this context it's treated as an > >> > unsigned int so the error handling can never trigger. The > >> > ->get_client_id() functions do not currently return any errors but > >> > I imagine that if they did, then the intention was to return > >> > VGA_SWITCHEROO_UNKNOWN_ID on error. Let's check for both negatives > >> > and UNKNOWN_ID so we'll catch it either way. > >> > > >> > Reported-by: Su Hui > >> > Closes: https://lore.kernel.org/all/20231026021056.850680-1-suhui@nfschina.com/ > >> > Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU id") > >> > Signed-off-by: Dan Carpenter > >> > --- > >> > drivers/gpu/vga/vga_switcheroo.c | 2 +- > >> > 1 file changed, 1 insertion(+), 1 deletion(-) > >> > > >> > diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c > >> > index 18f2c92beff8..216fb208eb31 100644 > >> > --- a/drivers/gpu/vga/vga_switcheroo.c > >> > +++ b/drivers/gpu/vga/vga_switcheroo.c > >> > @@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev *pdev, > >> > mutex_lock(&vgasr_mutex); > >> > if (vgasr_priv.active) { > >> > id = vgasr_priv.handler->get_client_id(vga_dev); > >> > - if (id < 0) { > >> > + if ((int)id < 0 || id == VGA_SWITCHEROO_UNKNOWN_ID) { > >> > >> Maybe we want to do something else here... see [1]. > >> > >> BR, > >> Jani. > >> > >> > >> [1] https://lore.kernel.org/r/CAHk-=wgg2A_iHNwf_JDjYJF=XHnKVGOjGp50FzVWniA2Z010bw@mail.gmail.com > >> > > > > I feel like my patch is good enough... I guess the concern here is that > > GCC could change enums to something else. I don't think that's likely as > > it would break a lot of code. The other option, which is a good option, > > is to change the function signature for vgasr_priv.handler->get_client_id() > > so that we do: > > > > ret = vgasr_priv.handler->get_client_id(vga_dev, &id); > > if (ret) > > return; > > > > That's better code, honestly. But I can't find motivation enough to do > > the work. > > The more I look at this, the more bonkers 4aaf448fa975 feels. > > Anyway, I don't think ->get_client_id() hooks should return negative > error codes, and indeed none of them do. None of them return > VGA_SWITCHEROO_UNKNOWN_ID either, but that would be a valid return. > > I suggest only checking for id == VGA_SWITCHEROO_UNKNOWN_ID. And doing > that in all the places that have that check, there are two more, but > they assign the return value to an int. So the int ret should be changed > to enum vga_switcheroo_unknown_id id I think. +1, this sounds like the cleanest way. > Any chance of finding enough motivation to do that? ;) For whom? ;) thanks, Takashi