From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753911AbcIKEom (ORCPT ); Sun, 11 Sep 2016 00:44:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46570 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753063AbcIKEok (ORCPT ); Sun, 11 Sep 2016 00:44:40 -0400 Date: Sat, 10 Sep 2016 21:44:38 -0700 From: Andrew Morton To: Alexey Khoroshilov , Alexandre Bounine , Matt Porter , linux-kernel@vger.kernel.org, ldv-project@linuxtesting.org Subject: Re: [PATCH] rapidio: avoid GFP_KERNEL in atomic context in riocm_send_close() Message-Id: <20160910214438.de89220445c47eb0d69c9f77@linux-foundation.org> In-Reply-To: <20160909212214.d520462c3c64c681a05a06b1@linux-foundation.org> References: <1473453815-15914-1-git-send-email-khoroshilov@ispras.ru> <20160909212214.d520462c3c64c681a05a06b1@linux-foundation.org> X-Mailer: Sylpheed 3.4.2 (GTK+ 2.24.28; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 9 Sep 2016 21:22:14 -0700 Andrew Morton wrote: > Why not just make `hdr' a local? It isn't very large and the code > becomes smaller and faster. Actually, doing it this way saves some code size and is faster: From: Andrew Morton Subject: drivers/rapidio/rio_cm.c: avoid GFP_KERNEL in atomic context riocm_send_close() is called from rio_cm_shutdown() under spin_lock_bh(idr_lock), but riocm_send_close() uses a GFP_KERNEL allocation. Fix this by making local `hdr' a local variable rather than obtaining it via kmalloc(). Found by Linux Driver Verification project (linuxtesting.org). Link: http://lkml.kernel.org/r/1473453815-15914-1-git-send-email-khoroshilov@ispras.ru Reported-by: Alexey Khoroshilov Cc: Alexandre Bounine Signed-off-by: Andrew Morton --- drivers/rapidio/rio_cm.c | 38 ++++++++++++++++--------------------- 1 file changed, 17 insertions(+), 21 deletions(-) diff -puN drivers/rapidio/rio_cm.c~drivers-rapidio-rio_cmc-avoid-gfp_kernel-in-atomic-context drivers/rapidio/rio_cm.c --- a/drivers/rapidio/rio_cm.c~drivers-rapidio-rio_cmc-avoid-gfp_kernel-in-atomic-context +++ a/drivers/rapidio/rio_cm.c @@ -1395,38 +1395,34 @@ static void riocm_ch_free(struct kref *r complete(&ch->comp_close); } +/* + * Send CH_CLOSE notification to the remote RapidIO device + */ static int riocm_send_close(struct rio_channel *ch) { - struct rio_ch_chan_hdr *hdr; int ret; - - /* - * Send CH_CLOSE notification to the remote RapidIO device - */ - - hdr = kzalloc(sizeof(*hdr), GFP_KERNEL); - if (hdr == NULL) - return -ENOMEM; - - hdr->bhdr.src_id = htonl(ch->loc_destid); - hdr->bhdr.dst_id = htonl(ch->rem_destid); - hdr->bhdr.src_mbox = cmbox; - hdr->bhdr.dst_mbox = cmbox; - hdr->bhdr.type = RIO_CM_CHAN; - hdr->ch_op = CM_CONN_CLOSE; - hdr->dst_ch = htons(ch->rem_channel); - hdr->src_ch = htons(ch->id); + struct rio_ch_chan_hdr hdr = { + .bhdr = { + .src_id = htonl(ch->loc_destid), + .dst_id = htonl(ch->rem_destid), + .src_mbox = cmbox, + .dst_mbox = cmbox, + .type = RIO_CM_CHAN, + }, + .ch_op = CM_CONN_CLOSE, + .dst_ch = htons(ch->rem_channel), + .src_ch = htons(ch->id), + }; /* ATTN: the function call below relies on the fact that underlying * add_outb_message() routine copies TX data into its internal transfer * buffer. Needs to be reviewed if switched to direct buffer mode. */ - ret = riocm_post_send(ch->cmdev, ch->rdev, hdr, sizeof(*hdr)); + ret = riocm_post_send(ch->cmdev, ch->rdev, &hdr, sizeof(hdr)); if (ret == -EBUSY && !riocm_queue_req(ch->cmdev, ch->rdev, - hdr, sizeof(*hdr))) + &hdr, sizeof(hdr))) return 0; - kfree(hdr); if (ret) riocm_error("ch(%d) send CLOSE failed (ret=%d)", ch->id, ret); _