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Message-Id: <20131212141654.876664708@infradead.org>
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Date: Thu, 12 Dec 2013 15:08:40 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Arjan van de Ven <arjan@linux.intel.com>, lenb@kernel.org,
        rjw@rjwysocki.net, Eliezer Tamir <eliezer.tamir@linux.intel.com>,
        rui.zhang@intel.com, jacob.jun.pan@linux.intel.com,
        Mike Galbraith <bitbucket@online.de>, Ingo Molnar <mingo@kernel.org>,
        hpa@zytor.com, paulmck@linux.vnet.ibm.com,
        Thomas Gleixner <tglx@linutronix.de>,
        John Stultz <john.stultz@linaro.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 05/15] sched, net: Clean up preempt_enable_no_resched() abuse
References: <20131212140835.729222186@infradead.org>
Content-Disposition: inline; filename=peterz-fixup-weird-preempt_enable_no_resched-usage.patch
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
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The only valid use of preempt_enable_no_resched() is if the very next
line is schedule() or if we know preemption cannot actually be enabled
by that statement due to known more preempt_count 'refs'.

Cc: rjw@rjwysocki.net
Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: rui.zhang@intel.com
Cc: jacob.jun.pan@linux.intel.com
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: hpa@zytor.com
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: lenb@kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
 net/ipv4/tcp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1623,11 +1623,11 @@ int tcp_recvmsg(struct kiocb *iocb, stru
 		    (len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) &&
 		    !sysctl_tcp_low_latency &&
 		    net_dma_find_channel()) {
-			preempt_enable_no_resched();
+			preempt_enable();
 			tp->ucopy.pinned_list =
 					dma_pin_iovec_pages(msg->msg_iov, len);
 		} else {
-			preempt_enable_no_resched();
+			preempt_enable();
 		}
 	}
 #endif