From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760631AbcDEWUF (ORCPT ); Tue, 5 Apr 2016 18:20:05 -0400 Received: from p3plsmtps2ded02.prod.phx3.secureserver.net ([208.109.80.59]:37822 "EHLO p3plsmtps2ded02.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760471AbcDEWUC (ORCPT ); Tue, 5 Apr 2016 18:20:02 -0400 x-originating-ip: 72.167.245.219 From: "K. Y. Srinivasan" To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, vkuznets@redhat.com, jasowang@redhat.com Cc: "K. Y. Srinivasan" Subject: [PATCH 3/8] Drivers: hv: vmbus: Use READ_ONCE() to read variables that are volatile Date: Tue, 5 Apr 2016 16:57:42 -0700 Message-Id: <1459900667-20367-3-git-send-email-kys@microsoft.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1459900667-20367-1-git-send-email-kys@microsoft.com> References: <1459900641-20328-1-git-send-email-kys@microsoft.com> <1459900667-20367-1-git-send-email-kys@microsoft.com> X-CMAE-Envelope: MS4wfHC2Wo5bCkb/hsRRNu63LsTiiERVVCeY/kY5IL5ukI+RPGYdBmtrBcdYl/NLaNfUUcmlsN36/uoeH0j72aEPBcEQa26HXGSN5s3xG7+EQ7PnBPkZbQAz qie4GtnD6JQ50gu9cFXA88iu5FqSjTe/YEpaS3h2Xq8PMjdMYn03ljIAqUlVBYU1I+Q66PcDGLYyOwWLBk4wSQGEgPhkhGo4rzSUZDQboqKtZ2AGDLA5mOUc CFA5DQVygVdgVAP6aYds7/IpmaRIHaiUKIJjWMTuqcowppJnPvX4Je/6FkZxUxz4dKE4kUo1S9kzyzV0PJOd6eKu1hcRPs4oQKRI+cRePPpcd1KJvWIKnOvO TLiXh9h1A2JWA3pGcFcvj3F8DqzkWuMFGBYO6k4VI9FCQqwZjkrG/Uu9bdRMXQgvWHycJgun Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use the READ_ONCE macro to access variabes that can change asynchronously. This is the recommended mechanism for dealing with "unsafe" compiler optimizations. Signed-off-by: K. Y. Srinivasan --- drivers/hv/ring_buffer.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 544362c..6ea1b55 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -69,7 +69,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi) static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) { mb(); - if (rbi->ring_buffer->interrupt_mask) + if (READ_ONCE(rbi->ring_buffer->interrupt_mask)) return false; /* check interrupt_mask before read_index */ @@ -78,7 +78,7 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) * This is the only case we need to signal when the * ring transitions from being empty to non-empty. */ - if (old_write == rbi->ring_buffer->read_index) + if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) return true; return false; @@ -117,7 +117,7 @@ static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi) */ mb(); - pending_sz = rbi->ring_buffer->pending_send_sz; + pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz); /* If the other end is not blocked on write don't bother. */ if (pending_sz == 0) return false; -- 1.7.4.1