| Message ID | 20131203222543.GQ8277@htj.dyndns.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Tue, Dec 03, 2013 at 05:25:43PM -0500, Tejun Heo wrote: > Hello, > > On Tue, Nov 26, 2013 at 11:37:03AM +0800, Wanlong Gao wrote: > > If kernel config CONFIG_DEBUG_FORCE_WEAK_PER_CPU=y, then the sparse will report non-static > > warnings like following: > > > > > /git/linux/fs/inode.c:74:8: warning: symbol 'nr_inodes' was not declared. Should it be static? > > > /git/linux/fs/inode.c:75:8: warning: symbol 'nr_unused' was not declared. Should it be static? > > > > > > $ vi +74 fs/inode.c > > > 73 > > > 74 static DEFINE_PER_CPU(unsigned long, nr_inodes); > > > 75 static DEFINE_PER_CPU(unsigned long, nr_unused); > > > 76 > > Hmmm, so, if FORCE_WEAK_PER_CPU is set or the arch needs WEAK_PER_CPU, > DEFINE_PER_CPU() explodes into mind-bending series of definitions to > ensure that the symbol is globally unique to avoid breaking weak decl > requirements on a few archs. In the process static is dropped from > the actual declaration and it's apparently missing extern decl in > front of it. > > Does the following patch make it go away? It should, but is there some reason why you couldn't make the definition on the line immediately below that static? > Thanks. > > diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h > index 57e890a..8c490cc 100644 > --- a/include/linux/percpu-defs.h > +++ b/include/linux/percpu-defs.h > @@ -69,6 +69,7 @@ > __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ > extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ > __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ > + extern __typeof__(type) name; \ > __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ > __typeof__(type) name > #else > -- > To unsubscribe from this list: send the line "unsubscribe linux-sparse" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/04/2013 06:25 AM, Tejun Heo wrote: > Hello, > > On Tue, Nov 26, 2013 at 11:37:03AM +0800, Wanlong Gao wrote: >> If kernel config CONFIG_DEBUG_FORCE_WEAK_PER_CPU=y, then the sparse will report non-static >> warnings like following: >> >>> /git/linux/fs/inode.c:74:8: warning: symbol 'nr_inodes' was not declared. Should it be static? >>> /git/linux/fs/inode.c:75:8: warning: symbol 'nr_unused' was not declared. Should it be static? >>> >>> $ vi +74 fs/inode.c >>> 73 >>> 74 static DEFINE_PER_CPU(unsigned long, nr_inodes); >>> 75 static DEFINE_PER_CPU(unsigned long, nr_unused); >>> 76 > > Hmmm, so, if FORCE_WEAK_PER_CPU is set or the arch needs WEAK_PER_CPU, > DEFINE_PER_CPU() explodes into mind-bending series of definitions to > ensure that the symbol is globally unique to avoid breaking weak decl > requirements on a few archs. In the process static is dropped from > the actual declaration and it's apparently missing extern decl in > front of it. > > Does the following patch make it go away? Goes away but comes new error: /git/linux/fs/inode.c:74:8: error: symbol 'nr_inodes' redeclared with different type (originally declared at /git/linux/fs/inode.c:74) - different address spaces /git/linux/fs/inode.c:75:8: error: symbol 'nr_unused' redeclared with different type (originally declared at /git/linux/fs/inode.c:75) - different address spaces /git/linux/fs/inode.c:835:8: error: symbol 'last_ino' redeclared with different type (originally declared at /git/linux/fs/inode.c:835) - different address spaces Thanks, Wanlong Gao > > Thanks. > > diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h > index 57e890a..8c490cc 100644 > --- a/include/linux/percpu-defs.h > +++ b/include/linux/percpu-defs.h > @@ -69,6 +69,7 @@ > __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ > extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ > __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ > + extern __typeof__(type) name; \ > __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ > __typeof__(type) name > #else > -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Dec 03, 2013 at 03:43:20PM -0800, Josh Triplett wrote: > > Does the following patch make it go away? > > It should, but is there some reason why you couldn't make the definition > on the line immediately below that static? Weak symbols can't be static. That's the point of the whole thing. Thanks.
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h index 57e890a..8c490cc 100644 --- a/include/linux/percpu-defs.h +++ b/include/linux/percpu-defs.h @@ -69,6 +69,7 @@ __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ + extern __typeof__(type) name; \ __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ __typeof__(type) name #else