tokuhirom's blog

valgrind でメモリリークの誤検出が起きる場合、suppression を指定する

valgrind は、問題がない場合でも誤検出することがママある。 そのような場合、suppressions ファイルを生成すればよい。

たとえば、dlopen() は内部でエラーメッセージ保存用のバッファを calloc で確保するが、このバッファは開放されないが、これはバグではないということになっている。See. https://sourceware.org/bugzilla/show_bug.cgi?id=14015

このような場合、以下のようにして、--gen-suppressions=all として、suppressions 設定をダンプさせることができる。

$ make -j 4 && valgrind --gen-suppressions=all --leak-check=full --show-leak-kinds=all ./a.out 
make: Nothing to be done for `all'.
==829== Memcheck, a memory error detector
==829== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==829== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==829== Command: ./a.out
==829==
==829==
==829== HEAP SUMMARY:
==829==     in use at exit: 32 bytes in 1 blocks
==829==   total heap usage: 437 allocs, 436 frees, 117,923 bytes allocated
==829==
==829== 32 bytes in 1 blocks are still reachable in loss record 1 of 1
==829==    at 0x4C2B974: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==829==    by 0x4E3668F: _dlerror_run (dlerror.c:141)
==829==    by 0x4E360C0: dlopen@@GLIBC_2.2.5 (dlopen.c:87)
==829==    by 0x407599: pone_compile_node (main.c:771)
==829==    by 0x407851: main (main.c:845)
==829==
{
    <insert_a_suppression_name_here>
    Memcheck:Leak
    match-leak-kinds: reachable
    fun:calloc
    fun:_dlerror_run
    fun:dlopen@@GLIBC_2.2.5
    fun:pone_compile_node
    fun:main
}
==829== LEAK SUMMARY:
==829==    definitely lost: 0 bytes in 0 blocks
==829==    indirectly lost: 0 bytes in 0 blocks
==829==      possibly lost: 0 bytes in 0 blocks
==829==    still reachable: 32 bytes in 1 blocks
==829==         suppressed: 0 bytes in 0 blocks
==829==
==829== For counts of detected and suppressed errors, rerun with: -v
==829== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)

この内容を t/myapp.supp などに保存する。そして、このファイルを指定して起動すると、以下のように、不要な警告をだまらせることができる。

$ make -j 4 && valgrind --suppressions=t/myapp.supp --leak-check=full --show-leak-kinds=all ./a.out
make: Nothing to be done for `all'.
==862== Memcheck, a memory error detector
==862== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==862== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==862== Command: ./a.out
==862==
==862==
==862== HEAP SUMMARY:
==862==     in use at exit: 32 bytes in 1 blocks
==862==   total heap usage: 437 allocs, 436 frees, 117,923 bytes allocated
==862==
==862== LEAK SUMMARY:
==862==    definitely lost: 0 bytes in 0 blocks
==862==    indirectly lost: 0 bytes in 0 blocks
==862==      possibly lost: 0 bytes in 0 blocks
==862==    still reachable: 0 bytes in 0 blocks
==862==         suppressed: 32 bytes in 1 blocks
==862==
==862== For counts of detected and suppressed errors, rerun with: -v
==862== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)
Created: 2015-12-19 10:14:59 +0900
Updated: 2015-12-19 10:14:59 +0900