modules: don't export section names of empty sections via sysfs

commit 35dead4235e2b67da7275b4122fed37099c2f462 upstream.

On the parisc architecture we face for each and every loaded kernel module
this kernel "badness warning":
  sysfs: cannot create duplicate filename '/module/ac97_bus/sections/.text'
  Badness at fs/sysfs/dir.c:487

Reason for that is, that on parisc all kernel modules do have multiple
.text sections due to the usage of the -ffunction-sections compiler flag
which is needed to reach all jump targets on this platform.

An objdump on such a kernel module gives:
Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .note.gnu.build-id 00000024  00000000  00000000  00000034  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  1 .text         00000000  00000000  00000000  00000058  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  2 .text.ac97_bus_match 0000001c  00000000  00000000  00000058  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  3 .text         00000000  00000000  00000000  000000d4  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
...
Since the .text sections are empty (size of 0 bytes) and won't be
loaded by the kernel module loader anyway, I don't see a reason
why such sections need to be listed under
/sys/module/<module_name>/sections/<section_name> either.

The attached patch does solve this issue by not exporting section
names which are empty.

This fixes bugzilla http://bugzilla.kernel.org/show_bug.cgi?id=14703

Signed-off-by: Helge Deller <deller@gmx.de>
CC: rusty@rustcorp.com.au
CC: akpm@linux-foundation.org
CC: James.Bottomley@HansenPartnership.com
CC: roland@redhat.com
CC: dave@hiauly1.hia.nrc.ca
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/kernel/module.c b/kernel/module.c
index 2d537186191f1c93ba39a2df1990741f690f3aac..cda4d7667d70fceb62858a96d1f1e0eb42b6471f 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1179,7 +1179,8 @@ static void add_sect_attrs(struct module *mod, unsigned int nsect,
 
        /* Count loaded sections and allocate structures */
        for (i = 0; i < nsect; i++)
-               if (sechdrs[i].sh_flags & SHF_ALLOC)
+               if (sechdrs[i].sh_flags & SHF_ALLOC
+                   && sechdrs[i].sh_size)
                        nloaded++;
        size[0] = ALIGN(sizeof(*sect_attrs)
                        + nloaded * sizeof(sect_attrs->attrs[0]),
@@ -1199,6 +1200,8 @@ static void add_sect_attrs(struct module *mod, unsigned int nsect,
        for (i = 0; i < nsect; i++) {
                if (! (sechdrs[i].sh_flags & SHF_ALLOC))
                        continue;
+               if (!sechdrs[i].sh_size)
+                       continue;
                sattr->address = sechdrs[i].sh_addr;
                sattr->name = kstrdup(secstrings + sechdrs[i].sh_name,
                                        GFP_KERNEL);