From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Ed7MWDsQ" Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA5DB10E for ; Tue, 21 Nov 2023 23:47:47 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id d9443c01a7336-1ce3084c2d1so54360975ad.3 for ; Tue, 21 Nov 2023 23:47:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700639267; x=1701244067; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=xSslZ87O8gm8ECVDRusqRDaovztLCrl5qgvaEZ6Clyk=; b=Ed7MWDsQfSXqjYq5NpP/K7pu9Y1cUr5rQnHFL78z7M7vWfV6mGv48UR20/9exZSpAc OxeyeNbWLiYl5StAUBDVyThQr67AwyDs71xHxtAaWa0SxQqIkDrLFvBh3M0UAw2+zgpT NkBbNA1+b3RB+NYEV71fmGdVwdbGnHqemZ0Bs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700639267; x=1701244067; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=xSslZ87O8gm8ECVDRusqRDaovztLCrl5qgvaEZ6Clyk=; b=BHYfiLsSEFvgXriYyn7X/Atx6zzY4VkhBwrJst1dT8KcPiH6PuvxdbPEFP0QRjuJvi +POfPEuiBmAKSSn4g3417b9t/aT1Ao+FYuQjIEIwHfzhzvt/uj9UsQ/O8FFphiSy7NUS avwwF71mFUiLFsG/rJ2jy5H8wtA2pV2xGvP6jyP6ZwqeDSrjLyaJdkh/tA3ynFn1Jjcz TTvWSJ3VoMk04HNmpUbwx7LT9+g4iiCS1boXA8TtfaZEkASFHvmZTOo9NFdjYrDj048D bUw2gHqf7+zEHjZp2aBSWG4IJpvMrS1XgH6UkJ0KcsWl+KNhqkkEMMdY8tJrh+uB7mE5 rRrQ== X-Gm-Message-State: AOJu0YziOPAhviqDtLkkx+cdS2Dclt3GycNpPtBB1FNo/htmSKJf/NR8 TFYITfodb8qQIGdhqICRgu+nlw== X-Google-Smtp-Source: AGHT+IECNClYO1LaWKWeX1noutwtFiNs4YaYyUIMp8wEuuTx1lDdfzGhFQs83fwaV5XDfo1fwtqQlQ== X-Received: by 2002:a17:902:b687:b0:1cf:6d46:9f2f with SMTP id c7-20020a170902b68700b001cf6d469f2fmr1501436pls.48.1700639267184; Tue, 21 Nov 2023 23:47:47 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:1aba:fb75:807e:7620]) by smtp.gmail.com with ESMTPSA id jd22-20020a170903261600b001ce160421aesm9182064plb.200.2023.11.21.23.47.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Nov 2023 23:47:46 -0800 (PST) Date: Wed, 22 Nov 2023 16:47:42 +0900 From: Sergey Senozhatsky To: Ricardo Ribalda Cc: Mauro Carvalho Chehab , Guenter Roeck , Tomasz Figa , Laurent Pinchart , Alan Stern , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Paul , Sakari Ailus Subject: Re: [PATCH v3 2/3] media: uvcvideo: Do not halt the device after disconnect Message-ID: <20231122074742.GB1465745@google.com> References: <20231121-guenter-mini-v3-0-d8a5eae2312b@chromium.org> <20231121-guenter-mini-v3-2-d8a5eae2312b@chromium.org> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231121-guenter-mini-v3-2-d8a5eae2312b@chromium.org> On (23/11/21 19:53), Ricardo Ribalda wrote: > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c > index 08fcd2ffa727..413c32867617 100644 > --- a/drivers/media/usb/uvc/uvc_driver.c > +++ b/drivers/media/usb/uvc/uvc_driver.c > @@ -2257,6 +2257,8 @@ static void uvc_disconnect(struct usb_interface *intf) > return; > > uvc_unregister_video(dev); > + /* Barrier needed to synchronize with uvc_video_stop_streaming(). */ > + smp_store_release(&dev->disconnected, true); > kref_put(&dev->ref, uvc_delete); > } [..] > +void uvc_video_stop_streaming(struct uvc_streaming *stream) > +{ > + uvc_video_stop_transfer(stream, 1); > + > + /* > + * Barrier needed to synchronize with uvc_disconnect(). > + * We cannot call usb_* functions on a disconnected USB device. > + */ > + if (!smp_load_acquire(&stream->dev->disconnected)) > + uvc_video_halt(stream); > + > uvc_video_clock_cleanup(stream); > } Can the following happen? CPU0 CPU1 uvc_disconnect() uvc_video_stop_streaming() usb_set_intfdata() uvc_unregister_video() if (!smp_load(&dev->disconnected)) uvc_video_halt() smp_store_release(&dev->disconnected, true); kref_put(&dev->ref, uvc_delete);