> On Aug 31, 2016, at 09:37, Arnd Bergmann <a...@arndb.de> wrote: > > On Wednesday, August 31, 2016 1:17:48 PM CEST Trond Myklebust wrote: >> What version of gcc are you using? I’m unable to reproduce with gcc 6.1.1.. > > This is also on 6.1.1 for ARM. Note that 6e8d666e9253 ("Disable > "maybe-uninitialized" warning globally") turned off those warnings, so > unless you explicitly pass -Wmaybe-uninitialized (e.g. by building with > "make W=1"), you won't get it. >
I’m not getting that error on gcc 6.1.1 for x86_64 with either “make W=1” or “make W=2”. “make W=3” does gives rise to one warning in nfs4_slot_get_seqid: /home/trondmy/devel/kernel/linux/fs/nfs/nfs4session.c: In function ‘nfs4_slot_get_seqid’: /home/trondmy/devel/kernel/linux/fs/nfs/nfs4session.c:184:10: warning: conversion to ‘int’ from ‘long int’ may alter its value [-Wconversion] return PTR_ERR(slot); ^~~~~~~~~~~~~ (which is another false positive) but that’s all... > The reason I'm still sending the patches for this warning is that > we do get a number of valid ones (this was the only false positive > out of the seven such warnings since last week). There is a Zen-like quality to IS_ERR() when it casts a const pointer to an unsigned long, back to a non-const pointer, and then back to an unsigned long before comparing it to another unsigned long cast constant negative integer. However, I’m not sure the C99 standard would agree that a positive test result implies we can assume that a simple cast of the same pointer to a signed long will result in a negative, non-zero valued errno. I suspect that if we really want to fix these false negatives, we should probably address that issue. Cheers Trond