Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753902AbdC1CaN (ORCPT ); Mon, 27 Mar 2017 22:30:13 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:59600 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753795AbdC1CaM (ORCPT ); Mon, 27 Mar 2017 22:30:12 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 28 Mar 2017 10:29:38 +0800 From: joechang@codeaurora.org To: minyard@acm.org Cc: Joeseph Chang , openipmi-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, anjiandi@codeaurora.org, Corey Minyard Subject: Re: [PATCH v2] ipmi: Fix kernel panic at ipmi_ssif_thread() In-Reply-To: References: <1490599902-45215-1-git-send-email-joechang@qti.qualcomm.com> Message-ID: User-Agent: Roundcube Webmail/1.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3608 Lines: 105 Hi Corey, I really appreciate your patience and detail code review. I re-generate new patch and send new patch to you. Please feel free to feedback to me if something need to modify from the new patch.. Thank you, Joseph. Corey Minyard 於 2017-03-27 20:32 寫到: > On 03/27/2017 02:31 AM, Joeseph Chang wrote: >> From: Joeseph Chang >> >> Since patch v1 touch ssif_info->multi_pos and ssif_info->multi_data >> after ssif_i2c_send(). msg_written_handler can be called at any time >> after ssif_i2c_send(). There is possible to have concurrent access to >> ssif_info->multi_pos or ssif_info->multi_data at msg_written_handler. >> >> Revert patch v1 and add new local pointer "i2c_data" which point to >> i2c data and size that will be sent out to avoid concurrent access in >> msg_written_handler(). >> >> Signed-off-by: Joeseph Chang >> --- >> drivers/char/ipmi/ipmi_ssif.c | 24 ++++++++++++------------ >> 1 file changed, 12 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/char/ipmi/ipmi_ssif.c >> b/drivers/char/ipmi/ipmi_ssif.c >> index 39346ee..f36f018 100644 >> --- a/drivers/char/ipmi/ipmi_ssif.c >> +++ b/drivers/char/ipmi/ipmi_ssif.c >> @@ -852,6 +852,7 @@ static void msg_written_handler(struct ssif_info >> *ssif_info, int result, >> unsigned char *data, unsigned int len) >> { >> int rv; >> + unsigned char *i2c_data; > > The variable should be in the block where it is used. The basic rule > is to limit scope as much as possible. > > The name is also a little vague, though not terrible. > >> /* We are single-threaded here, so no need for a lock. */ >> if (result < 0) { >> @@ -899,13 +900,22 @@ static void msg_written_handler(struct ssif_info >> *ssif_info, int result, >> left = 32; >> /* Length byte. */ >> ssif_info->multi_data[ssif_info->multi_pos] = left; >> + i2c_data = ssif_info->multi_data + ssif_info->multi_pos; >> + ssif_info->multi_pos += left; >> + if (left < 32) >> + /* >> + * Write is finished. Note that we must end >> + * with a write of less than 32 bytes to >> + * complete the transaction, even if it is >> + * zero bytes. >> + */ >> + ssif_info->multi_data = NULL; > > Can you make this change not relative to the previous change? Just do > a "git rebase -i ...." and squash the > changes. > > I saw your previous emails, but I can't take those because of the > comments at the top and the text from > the reply. You can add comments to a submission that don't go into > git, just put them after the '---" in > the header. > > Thanks, > > -corey > >> rv = ssif_i2c_send(ssif_info, msg_written_handler, >> I2C_SMBUS_WRITE, >> SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE, >> - ssif_info->multi_data + ssif_info->multi_pos, >> + i2c_data, >> I2C_SMBUS_BLOCK_DATA); >> - >> if (rv < 0) { >> /* request failed, just return the error. */ >> ssif_inc_stat(ssif_info, send_errors); >> @@ -914,16 +924,6 @@ static void msg_written_handler(struct ssif_info >> *ssif_info, int result, >> pr_info("Error from i2c_non_blocking_op(3)\n"); >> msg_done_handler(ssif_info, -EIO, NULL, 0); >> } >> - >> - ssif_info->multi_pos += left; >> - if (left < 32) >> - /* >> - * Write is finished. Note that we must end >> - * with a write of less than 32 bytes to >> - * complete the transaction, even if it is >> - * zero bytes. >> - */ >> - ssif_info->multi_data = NULL; >> } else { >> /* Ready to request the result. */ >> unsigned long oflags, *flags;