Messages in this thread | | | Date | Thu, 8 Feb 2018 16:53:50 +0300 | From | Dan Carpenter <> | Subject | Re: [PATCH] scripts/coccinelle/misc/shift.cocci: detect < or > that should be a shift |
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On Thu, Feb 08, 2018 at 01:53:54PM +0100, Julia Lawall wrote: > This checks for a comparison using < or > between two constants, > considering both explicit constants (1, 2, etc) and macros defined > with #define. False positives are possible in the latter case, when > a macro may have multiple possible definitions and it is indeed > necessary to check the value. There are currently two such false > positives, in drivers/net/ethernet/chelsio/cxgb3/sge.c: > > q->fl[0].use_pages = FL0_PG_CHUNK_SIZE > 0; > q->fl[1].use_pages = FL1_PG_CHUNK_SIZE > 0; >
We could eliminate both these false postives by ignoring >> vs >. Did searching for > actually find any bugs? I think you were right that right shifting a constant is way less common than left shifting and I have some smatch scripts where I ignore right shifting bugs.
On the other hand, two false positives are not a big deal.
regards, dan carpenter
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