Re: [PATCH] atm: Cleanup redundant tests on unsigned

Re: [PATCH] atm: Cleanup redundant tests on unsigned

[Eric Dumazet]

Roel Kluin a écrit :
> The variables are unsigned so the `< 0' test always fails, the
> other part of the test catches wrapped values.
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---

I believe such patches were posted in the past.

General consensus is that compiler is able to do this optimization for us,
and reader doesnt have to ask to himself : "Is the test safe enough ?"

[PATCH] atm: Cleanup redundant tests on unsigned

[Roel Kluin]

The variables are unsigned so the `< 0' test always fails, the
other part of the test catches wrapped values.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
 drivers/atm/fore200e.c |    4 ++--
 drivers/atm/he.c       |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/atm/fore200e.c b/drivers/atm/fore200e.c
index f766cc4..bc53fed 100644
--- a/drivers/atm/fore200e.c
+++ b/drivers/atm/fore200e.c
@@ -2906,8 +2906,8 @@ fore200e_proc_read(struct atm_dev *dev, loff_t* pos, char* page)
 	u32 media_index    = FORE200E_MEDIA_INDEX(fore200e->bus->read(&fore200e->cp_queues->media_type));
 	u32 oc3_index;
 
-	if ((media_index < 0) || (media_index > 4))
-	    media_index = 5;
+	if (media_index > 4)
+		media_index = 5;
 	
 	switch (fore200e->loop_mode) {
 	    case ATM_LM_NONE:    oc3_index = 0;
diff --git a/drivers/atm/he.c b/drivers/atm/he.c
index 7066703..e906658 100644
--- a/drivers/atm/he.c
+++ b/drivers/atm/he.c
@@ -2739,7 +2739,7 @@ he_ioctl(struct atm_dev *atm_dev, unsigned int cmd, void __user *arg)
 			spin_lock_irqsave(&he_dev->global_lock, flags);
 			switch (reg.type) {
 				case HE_REGTYPE_PCI:
-					if (reg.addr < 0 || reg.addr >= HE_REGMAP_SIZE) {
+					if (reg.addr >= HE_REGMAP_SIZE) {
 						err = -EINVAL;
 						break;
 					}

Re: [PATCH] atm: Cleanup redundant tests on unsigned

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 23 Oct 2009 18:08:30 +0200

> Roel Kluin a écrit :
>> The variables are unsigned so the `< 0' test always fails, the
>> other part of the test catches wrapped values.
>> 
>> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
>> ---
> 
> I believe such patches were posted in the past.
> 
> General consensus is that compiler is able to do this optimization for us,
> and reader doesnt have to ask to himself : "Is the test safe enough ?"

Conversely, the reader can say "Wow this can be negative?  There's
tests missing elsewhere! ... oh, nevermind it's unsigned"

That really wastes people's time too.

I suspect I'll apply these patches. :-)

Re: [PATCH] atm: Cleanup redundant tests on unsigned

[David Miller]

From: Roel Kluin <roel.kluin@gmail.com>
Date: Fri, 23 Oct 2009 18:09:55 +0200

> The variables are unsigned so the `< 0' test always fails, the
> other part of the test catches wrapped values.
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>

Applied.