Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754166AbaGKOip (ORCPT ); Fri, 11 Jul 2014 10:38:45 -0400 Received: from mail.mev.co.uk ([62.49.15.74]:59338 "EHLO mail.mev.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751649AbaGKOio (ORCPT ); Fri, 11 Jul 2014 10:38:44 -0400 From: Ian Abbott To: , , Cc: , , , , Andrey Utkin Subject: [PATCH v3] drivers/staging/comedi/drivers/ni_atmio16d.c: remove pointless condition Date: Fri, 11 Jul 2014 15:38:30 +0100 Message-Id: <1405089510-23182-1-git-send-email-abbotti@mev.co.uk> X-Mailer: git-send-email 2.0.0 In-Reply-To: <1405089127-21646-1-git-send-email-abbotti@mev.co.uk> References: <1405089127-21646-1-git-send-email-abbotti@mev.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrey Utkin From: Andrey Utkin The issue was discovered with static analysis and has two instances in this file. The code looks like this if (x < 65536000) { ... } else if (x < 655360000) { ... } else if (x <= 0xffffffff /* 6553600000 */) { ... } else if (x <= 0xffffffff /* 65536000000 */) { ... } The meaning of this block is to select appropriate clock frequency for interval timer basing on "x", which is amount of time. Notes: 1. That last condition matches previous one - that's the issue. 2. Decimal numbers in comments don't match hex numbers in expressions. But in first case the numbers have same order, while in the second case the hex number is the same, and the decimal one is 10 times bigger. 3. Actually type of "x" is "unsigned int", so its exact upper limit is not obviously known. 4. There's no "else" block. So it makes sense to make an "else" block from last "else if" case. The code inside the block seems correct for such usage. [ Actually, get rid of the final "else if" case and change the next-to-last "else if" case to an "else" as the upper limit of "x" _is_ known to be 0xffffffff (UINT_MAX), which is less than 6553600000 -- Ian ] Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=79871 Reported-by: David Binderman Signed-off-by: Andrey Utkin Signed-off-by: Ian Abbott --- v2: Removed final "else if" block and changed preceding "else if" block to "else" block as the condition is always true due to limited range of "unsigned int". -- Ian v3: Corrected subject line I messed up in v2. -- Ian --- drivers/staging/comedi/drivers/ni_atmio16d.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/drivers/staging/comedi/drivers/ni_atmio16d.c b/drivers/staging/comedi/drivers/ni_atmio16d.c index 6ad27f5..b1b4744 100644 --- a/drivers/staging/comedi/drivers/ni_atmio16d.c +++ b/drivers/staging/comedi/drivers/ni_atmio16d.c @@ -335,12 +335,9 @@ static int atmio16d_ai_cmd(struct comedi_device *dev, } else if (cmd->convert_arg < 655360000) { base_clock = CLOCK_100_KHZ; timer = cmd->convert_arg / 10000; - } else if (cmd->convert_arg <= 0xffffffff /* 6553600000 */) { + } else /* cmd->convert_arg < 6553600000 */ { base_clock = CLOCK_10_KHZ; timer = cmd->convert_arg / 100000; - } else if (cmd->convert_arg <= 0xffffffff /* 65536000000 */) { - base_clock = CLOCK_1_KHZ; - timer = cmd->convert_arg / 1000000; } outw(0xFF03, dev->iobase + AM9513A_COM_REG); outw(base_clock, dev->iobase + AM9513A_DATA_REG); @@ -403,12 +400,9 @@ static int atmio16d_ai_cmd(struct comedi_device *dev, } else if (cmd->scan_begin_arg < 655360000) { base_clock = CLOCK_100_KHZ; timer = cmd->scan_begin_arg / 10000; - } else if (cmd->scan_begin_arg < 0xffffffff /* 6553600000 */) { + } else /* cmd->scan_begin_arg < 6553600000 */ { base_clock = CLOCK_10_KHZ; timer = cmd->scan_begin_arg / 100000; - } else if (cmd->scan_begin_arg < 0xffffffff /* 65536000000 */) { - base_clock = CLOCK_1_KHZ; - timer = cmd->scan_begin_arg / 1000000; } outw(0xFF02, dev->iobase + AM9513A_COM_REG); outw(base_clock, dev->iobase + AM9513A_DATA_REG); -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/