| Message ID | 20200505140407.373983-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | omapfb: don't annotate dss_conv_list as __initdata | expand |
On Tue, 5 May 2020 at 16:04, Arnd Bergmann <arnd@arndb.de> wrote: > > With the kcsan changes, __read_once_size() is not inlined, but > clang can decide to emit a version that hardcodes the address, which > in turn triggers a warning for dss_conv_list being __initdata but > __read_once_size() not being __init: > > WARNING: modpost: vmlinux.o(.text+0x6e4d7a): Section mismatch in > reference from the function __read_once_size() to the variable > .init.data:dss_conv_list > The function __read_once_size() references > the variable __initdata dss_conv_list. > This is often because __read_once_size lacks a __initdata > annotation or the annotation of dss_conv_list is wrong. > > This is clearly a false positive warning, but it's hard to tell > who is to blame for it. Work around it by removing the __initdata > annotation, wasting the space of two pointers in return for getting > rid of the warning. > > Fixes: dfd402a4c4ba ("kcsan: Add Kernel Concurrency Sanitizer infrastructure") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> [+Cc Will] I think Will is working on a series that completely overhauls READ_ONCE/WRITE_ONCE, also getting rid of __read_once_size() in the process, which would make this patch redundant. If we can live with this warning until the new READ_ONCE/WRITE_ONCE gets merged, we can probably keep things as-is for now. Thanks, -- Marco > --- > drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c b/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c > index 0ae0cab252d3..29fdff9c95f6 100644 > --- a/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c > +++ b/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c > @@ -19,7 +19,7 @@ > #include <linux/slab.h> > #include <linux/list.h> > > -static struct list_head dss_conv_list __initdata; > +static struct list_head dss_conv_list; > > static const char prefix[] __initconst = "omapdss,"; > > -- > 2.26.0 >
On Tue, May 5, 2020 at 4:12 PM 'Marco Elver' via Clang Built Linux <clang-built-linux@googlegroups.com> wrote: > On Tue, 5 May 2020 at 16:04, Arnd Bergmann <arnd@arndb.de> wrote: > > With the kcsan changes, __read_once_size() is not inlined, but > > clang can decide to emit a version that hardcodes the address, which > > in turn triggers a warning for dss_conv_list being __initdata but > > __read_once_size() not being __init: > > > > WARNING: modpost: vmlinux.o(.text+0x6e4d7a): Section mismatch in > > reference from the function __read_once_size() to the variable > > .init.data:dss_conv_list > > The function __read_once_size() references > > the variable __initdata dss_conv_list. > > This is often because __read_once_size lacks a __initdata > > annotation or the annotation of dss_conv_list is wrong. > > > > This is clearly a false positive warning, but it's hard to tell > > who is to blame for it. Work around it by removing the __initdata > > annotation, wasting the space of two pointers in return for getting > > rid of the warning. > > > > Fixes: dfd402a4c4ba ("kcsan: Add Kernel Concurrency Sanitizer infrastructure") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > [+Cc Will] > > I think Will is working on a series that completely overhauls > READ_ONCE/WRITE_ONCE, also getting rid of __read_once_size() in the > process, which would make this patch redundant. If we can live with > this warning until the new READ_ONCE/WRITE_ONCE gets merged, we can > probably keep things as-is for now. Ok, let's drop this one for now. Arnd
diff --git a/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c b/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c index 0ae0cab252d3..29fdff9c95f6 100644 --- a/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c +++ b/drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c @@ -19,7 +19,7 @@ #include <linux/slab.h> #include <linux/list.h> -static struct list_head dss_conv_list __initdata; +static struct list_head dss_conv_list; static const char prefix[] __initconst = "omapdss,";
With the kcsan changes, __read_once_size() is not inlined, but clang can decide to emit a version that hardcodes the address, which in turn triggers a warning for dss_conv_list being __initdata but __read_once_size() not being __init: WARNING: modpost: vmlinux.o(.text+0x6e4d7a): Section mismatch in reference from the function __read_once_size() to the variable .init.data:dss_conv_list The function __read_once_size() references the variable __initdata dss_conv_list. This is often because __read_once_size lacks a __initdata annotation or the annotation of dss_conv_list is wrong. This is clearly a false positive warning, but it's hard to tell who is to blame for it. Work around it by removing the __initdata annotation, wasting the space of two pointers in return for getting rid of the warning. Fixes: dfd402a4c4ba ("kcsan: Add Kernel Concurrency Sanitizer infrastructure") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/video/fbdev/omap2/omapfb/dss/omapdss-boot-init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)