From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 455ADC433FE for ; Tue, 16 Nov 2021 00:32:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 356BD619E8 for ; Tue, 16 Nov 2021 00:32:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343828AbhKPAew (ORCPT ); Mon, 15 Nov 2021 19:34:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:45212 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343959AbhKOTWb (ORCPT ); Mon, 15 Nov 2021 14:22:31 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 48B58604D1; Mon, 15 Nov 2021 18:49:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637002175; bh=XjXIU3AqPDWK1zsJOZsPevZkNoJfHbMwTbUH/TcPL1c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Mx64++QGZoXEqiA19lSBFjJM0VL3XZQExTdn69mNdoJ1YCj95MK+HHm7mqveSAcGp dv+BMOtzKp13OpT08s8j6+h3+sT2uunYOCpasNxh30UjYbI1StVF6FPymIofcIdj+5 7KncrEGk06OCZ737LzpyILy0PIwXQriymzXQMfKY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Schmitz , linux-block@vger.kernel.org, Tetsuo Handa , Jens Axboe , Sasha Levin Subject: [PATCH 5.15 449/917] block: ataflop: fix breakage introduced at blk-mq refactoring Date: Mon, 15 Nov 2021 17:59:04 +0100 Message-Id: <20211115165444.006421431@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165428.722074685@linuxfoundation.org> References: <20211115165428.722074685@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michael Schmitz [ Upstream commit 86d46fdaa12ae5befc16b8d73fc85a3ca0399ea6 ] Refactoring of the Atari floppy driver when converting to blk-mq has broken the state machine in not-so-subtle ways: finish_fdc() must be called when operations on the floppy device have completed. This is crucial in order to relase the ST-DMA lock, which protects against concurrent access to the ST-DMA controller by other drivers (some DMA related, most just related to device register access - broken beyond compare, I know). When rewriting the driver's old do_request() function, the fact that finish_fdc() was called only when all queued requests had completed appears to have been overlooked. Instead, the new request function calls finish_fdc() immediately after the last request has been queued. finish_fdc() executes a dummy seek after most requests, and this overwrites the state machine's interrupt hander that was set up to wait for completion of the read/write request just prior. To make matters worse, finish_fdc() is called before device interrupts are re-enabled, making certain that the read/write interupt is missed. Shifting the finish_fdc() call into the read/write request completion handler ensures the driver waits for the request to actually complete. With a queue depth of 2, we won't see long request sequences, so calling finish_fdc() unconditionally just adds a little overhead for the dummy seeks, and keeps the code simple. While we're at it, kill ataflop_commit_rqs() which does nothing but run finish_fdc() unconditionally, again likely wiping out an in-flight request. Signed-off-by: Michael Schmitz Fixes: 6ec3938cff95 ("ataflop: convert to blk-mq") CC: linux-block@vger.kernel.org CC: Tetsuo Handa Link: https://lore.kernel.org/r/20211019061321.26425-1-schmitzmic@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/ataflop.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c index a093644ac39fb..bbb64331cf8f4 100644 --- a/drivers/block/ataflop.c +++ b/drivers/block/ataflop.c @@ -653,9 +653,6 @@ static inline void copy_buffer(void *from, void *to) *p2++ = *p1++; } - - - /* General Interrupt Handling */ static void (*FloppyIRQHandler)( int status ) = NULL; @@ -1228,6 +1225,7 @@ static void fd_rwsec_done1(int status) } else { /* all sectors finished */ + finish_fdc(); fd_end_request_cur(BLK_STS_OK); } return; @@ -1475,15 +1473,6 @@ static void setup_req_params( int drive ) ReqTrack, ReqSector, (unsigned long)ReqData )); } -static void ataflop_commit_rqs(struct blk_mq_hw_ctx *hctx) -{ - spin_lock_irq(&ataflop_lock); - atari_disable_irq(IRQ_MFP_FDC); - finish_fdc(); - atari_enable_irq(IRQ_MFP_FDC); - spin_unlock_irq(&ataflop_lock); -} - static blk_status_t ataflop_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd) { @@ -1491,6 +1480,8 @@ static blk_status_t ataflop_queue_rq(struct blk_mq_hw_ctx *hctx, int drive = floppy - unit; int type = floppy->type; + DPRINT(("Queue request: drive %d type %d last %d\n", drive, type, bd->last)); + spin_lock_irq(&ataflop_lock); if (fd_request) { spin_unlock_irq(&ataflop_lock); @@ -1550,8 +1541,6 @@ static blk_status_t ataflop_queue_rq(struct blk_mq_hw_ctx *hctx, setup_req_params( drive ); do_fd_action( drive ); - if (bd->last) - finish_fdc(); atari_enable_irq( IRQ_MFP_FDC ); out: @@ -1962,7 +1951,6 @@ static const struct block_device_operations floppy_fops = { static const struct blk_mq_ops ataflop_mq_ops = { .queue_rq = ataflop_queue_rq, - .commit_rqs = ataflop_commit_rqs, }; static int ataflop_alloc_disk(unsigned int drive, unsigned int type) -- 2.33.0