linux-kernel - Re: [PATCH 4/5] [media] winbond-cir: One variable and its check less in wbcir

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <19c2ed0f7c2ab3c641d681f5c4e671d9@hardeman.nu>
Date:   Wed, 19 Oct 2016 13:10:05 +0000
From:   "David Härdeman" <david@...deman.nu>
To:     "Sean Young" <sean@...s.org>,
        "SF Markus Elfring" <elfring@...rs.sourceforge.net>
Cc:     linux-media@...r.kernel.org,
        "Mauro Carvalho Chehab" <mchehab@...nel.org>,
        "LKML" <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        "Julia Lawall" <julia.lawall@...6.fr>
Subject: Re: [PATCH 4/5] [media] winbond-cir: One variable and its check
 less in wbcir_shutdown() after error detection

October 15, 2016 3:30 PM, "Sean Young" <sean@...s.org> wrote:
> On Fri, Oct 14, 2016 at 01:44:02PM +0200, SF Markus Elfring wrote:
> 
>> From: Markus Elfring <elfring@...rs.sourceforge.net>
>> Date: Fri, 14 Oct 2016 12:48:41 +0200
>> 
>> The local variable "do_wake" was set to "false" after an invalid system
>> setting was detected so that a bit of error handling was triggered.
>> 
>> * Replace these assignments by direct jumps to the source code with the
>> desired exception handling.
>> 
>> * Delete this status variable and a corresponding check which became
>> unnecessary with this refactoring.
>> 
>> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
>> ---
>> drivers/media/rc/winbond-cir.c | 78 ++++++++++++++++++------------------------
>> 1 file changed, 34 insertions(+), 44 deletions(-)
>> 
>> diff --git a/drivers/media/rc/winbond-cir.c b/drivers/media/rc/winbond-cir.c
>> index 9d05e17..3d286b9 100644
>> --- a/drivers/media/rc/winbond-cir.c
>> +++ b/drivers/media/rc/winbond-cir.c
>> @@ -699,16 +699,13 @@ wbcir_shutdown(struct pnp_dev *device)
>> {
>> struct device *dev = &device->dev;
>> struct wbcir_data *data = pnp_get_drvdata(device);
>> - bool do_wake = true;
>> u8 match[11];
>> u8 mask[11];
>> u8 rc6_csl;
>> int i;
>> 
>> - if (wake_sc == INVALID_SCANCODE || !device_may_wakeup(dev)) {
>> - do_wake = false;
>> - goto finish;
>> - }
>> + if (wake_sc == INVALID_SCANCODE || !device_may_wakeup(dev))
>> + goto clear_bits;
>> 
>> rc6_csl = 0;
>> memset(match, 0, sizeof(match));
>> @@ -716,9 +713,8 @@ wbcir_shutdown(struct pnp_dev *device)
>> switch (protocol) {
>> case IR_PROTOCOL_RC5:
>> if (wake_sc > 0xFFF) {
>> - do_wake = false;
>> dev_err(dev, "RC5 - Invalid wake scancode\n");
>> - break;
>> + goto clear_bits;
>> }
>> 
>> /* Mask = 13 bits, ex toggle */
>> @@ -735,9 +731,8 @@ wbcir_shutdown(struct pnp_dev *device)
>> 
>> case IR_PROTOCOL_NEC:
>> if (wake_sc > 0xFFFFFF) {
>> - do_wake = false;
>> dev_err(dev, "NEC - Invalid wake scancode\n");
>> - break;
>> + goto clear_bits;
>> }
>> 
>> mask[0] = mask[1] = mask[2] = mask[3] = 0xFF;
>> @@ -757,9 +752,8 @@ wbcir_shutdown(struct pnp_dev *device)
>> 
>> if (wake_rc6mode == 0) {
>> if (wake_sc > 0xFFFF) {
>> - do_wake = false;
>> dev_err(dev, "RC6 - Invalid wake scancode\n");
>> - break;
>> + goto clear_bits;
>> }
>> 
>> /* Command */
>> @@ -813,9 +807,8 @@ wbcir_shutdown(struct pnp_dev *device)
>> } else if (wake_sc <= 0x007FFFFF) {
>> rc6_csl = 60;
>> } else {
>> - do_wake = false;
>> dev_err(dev, "RC6 - Invalid wake scancode\n");
>> - break;
>> + goto clear_bits;
>> }
>> 
>> /* Header */
>> @@ -825,49 +818,38 @@ wbcir_shutdown(struct pnp_dev *device)
>> mask[i++] = 0x0F;
>> 
>> } else {
>> - do_wake = false;
>> dev_err(dev, "RC6 - Invalid wake mode\n");
>> + goto clear_bits;
>> }
>> 
>> break;
>> 
>> default:
>> - do_wake = false;
>> - break;
>> + goto clear_bits;
>> }
>> 
>> -finish:
>> - if (do_wake) {
>> - /* Set compare and compare mask */
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_INDEX,
>> - WBCIR_REGSEL_COMPARE | WBCIR_REG_ADDR0,
>> - 0x3F);
>> - outsb(data->wbase + WBCIR_REG_WCEIR_DATA, match, 11);
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_INDEX,
>> - WBCIR_REGSEL_MASK | WBCIR_REG_ADDR0,
>> - 0x3F);
>> - outsb(data->wbase + WBCIR_REG_WCEIR_DATA, mask, 11);
>> -
>> - /* RC6 Compare String Len */
>> - outb(rc6_csl, data->wbase + WBCIR_REG_WCEIR_CSL);
>> -
>> - /* Clear status bits NEC_REP, BUFF, MSG_END, MATCH */
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_STS, 0x17, 0x17);
>> + /* Set compare and compare mask */
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_INDEX,
>> + WBCIR_REGSEL_COMPARE | WBCIR_REG_ADDR0,
>> + 0x3F);
>> + outsb(data->wbase + WBCIR_REG_WCEIR_DATA, match, 11);
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_INDEX,
>> + WBCIR_REGSEL_MASK | WBCIR_REG_ADDR0,
>> + 0x3F);
>> + outsb(data->wbase + WBCIR_REG_WCEIR_DATA, mask, 11);
>> 
>> - /* Clear BUFF_EN, Clear END_EN, Set MATCH_EN */
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_EV_EN, 0x01, 0x07);
>> + /* RC6 Compare String Len */
>> + outb(rc6_csl, data->wbase + WBCIR_REG_WCEIR_CSL);
>> 
>> - /* Set CEIR_EN */
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_CTL, 0x01, 0x01);
>> -
>> - } else {
>> - /* Clear BUFF_EN, Clear END_EN, Clear MATCH_EN */
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_EV_EN, 0x00, 0x07);
>> + /* Clear status bits NEC_REP, BUFF, MSG_END, MATCH */
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_STS, 0x17, 0x17);
>> 
>> - /* Clear CEIR_EN */
>> - wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_CTL, 0x00, 0x01);
>> - }
>> + /* Clear BUFF_EN, Clear END_EN, Set MATCH_EN */
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_EV_EN, 0x01, 0x07);
>> 
>> + /* Set CEIR_EN */
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_CTL, 0x01, 0x01);
>> +set_irqmask:
>> /*
>> * ACPI will set the HW disable bit for SP3 which means that the
>> * output signals are left in an undefined state which may cause
>> @@ -876,6 +858,14 @@ wbcir_shutdown(struct pnp_dev *device)
>> */
>> wbcir_set_irqmask(data, WBCIR_IRQ_NONE);
>> disable_irq(data->irq);
>> + return;
>> +clear_bits:
>> + /* Clear BUFF_EN, Clear END_EN, Clear MATCH_EN */
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_EV_EN, 0x00, 0x07);
>> +
>> + /* Clear CEIR_EN */
>> + wbcir_set_bits(data->wbase + WBCIR_REG_WCEIR_CTL, 0x00, 0x01);
>> + goto set_irqmask;
> 
> I'm not convinced that adding a goto which goes backwards is making this
> code any more readible, just so that a local variable can be dropped.
> 

Agreed.