From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:37757 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753021AbbETNx4 (ORCPT ); Wed, 20 May 2015 09:53:56 -0400 From: Kalle Valo To: Larry Finger Cc: linux-wireless@vger.kernel.org, Vincent Fann , Shao Fu , Stable Subject: Re: [PATCH 4.1] rtlwifi: Remove the clear interrupt routine from all drivers References: <1431743367-10059-1-git-send-email-Larry.Finger@lwfinger.net> Date: Wed, 20 May 2015 16:53:51 +0300 In-Reply-To: <1431743367-10059-1-git-send-email-Larry.Finger@lwfinger.net> (Larry Finger's message of "Fri, 15 May 2015 21:29:27 -0500") Message-ID: <877fs39wy8.fsf@kamboji.qca.qualcomm.com> (sfid-20150520_155400_827418_A764CA92) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: Larry Finger writes: > From: Vincent Fann > > Several of these drivers have there TX randomly blocked for 3~5 seconds while > measuring tx throughput (iperf). The root couse happens in rtl_pci_flush(). > The function uses a while-loop to wait for TX queue length to decrease to 0. > The TX queue length counts the number of packets that are queued in the driver. > The driver relys on the TX OK interrupt to return skb and reduce TX queue length. > > The interrupt subroutine disables interupts, reads the interrupt registers, and > then clears the registers in the beginning of _rtl_pci_interrupt(). After all > interupts process are finished, the driver invokes enable_interrupt() to enable > interupts. This behavior is normal for an interrupt subroutine. > > But enable_interrupt() invokes clear_interrupt() again. This unexpected interrupt > clearing may cleari me fresh TX OK interrupts. These missing interrupts cause TX > queue length to never reduce to 0i, which causes rtl_pci_flush() to be stuck in > unterminated while-loop. > > This patch removes clear_interrupt() in enable_interrupt() to avoid this behavior. > > Signed-off-by: Vincent Fann > Signed-off-by: Shao Fu > Signed-off-by: Larry Finger > Cc: Stable [3.18+] > --- > > Kalle, > > This patch is a little large for the current kernel and stable; however, it only > deletes code that is clearly wrong. I hope it will be OK. This isn't a recent regression nor a crasher (or similar) so I can't really justify to send this to 4.1 this late. The way I see it this could easily wait for 4.2, right? -- Kalle Valo