Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH v3] err.h: allow IS_ERR_VALUE to handle properly more types | Date | Thu, 04 Feb 2016 16:00:09 +0100 |
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On Thursday 04 February 2016 15:44:51 Andrzej Hajda wrote: > On 02/04/2016 01:40 PM, Arnd Bergmann wrote: > > On Wednesday 03 February 2016 14:15:28 Andrzej Hajda wrote: > >> diff --git a/include/linux/err.h b/include/linux/err.h > >> index 56762ab..b7d4a9f 100644 > >> --- a/include/linux/err.h > >> +++ b/include/linux/err.h > >> @@ -18,7 +18,9 @@ > >> > >> #ifndef __ASSEMBLY__ > >> > >> -#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO) > >> +#define IS_ERR_VALUE(x) ((typeof(x))(-1) <= 0 \ > >> + ? unlikely((x) <= -1) \ > >> + : unlikely((x) >= (typeof(x))-MAX_ERRNO)) > >> > >> static inline void * __must_check ERR_PTR(long error) > >> { > >> > > This has caused a warning to reappear that I had fixed before: > > > > fs/gfs2/dir.c: In function 'get_first_leaf': > > fs/gfs2/dir.c:802:9: warning: 'leaf_no' may be used uninitialized in this function [-Wmaybe-uninitialized] > > error = get_leaf(dip, leaf_no, bh_out); > > ^ > > fs/gfs2/dir.c: In function 'dir_split_leaf': > > fs/gfs2/dir.c:1021:8: warning: 'leaf_no' may be used uninitialized in this function [-Wmaybe-uninitialized] > > error = get_leaf(dip, leaf_no, &obh); > > What gcc/arch/build options do you use? I cannot reproduce it in my > environment. >
I use an ARM gcc-5.3 with an allmodconfig kernel and CONFIG_CC_OPTIMIZE_FOR_SIZE disabled. I see the same warning with any gcc version since 4.9, but not earlier.
With the IS_ERR_VALUE() macro I sent, I don't see the warning on any gcc version. I have now also checked that the behavior on x86 gcc-.4.9 is the same that I see on ARM (I don't have a large collection of x86 gcc versions though): same warning with linux-next, no warning with my version or after reverting your patch.
Arnd
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