diff options
| author | Andi Kleen <ak@muc.de> | 2003-11-07 00:32:55 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@home.osdl.org> | 2003-11-07 00:32:55 -0800 |
| commit | 6077b1d358b09e4fb02ac9d5a3bed4884f7afe86 (patch) | |
| tree | fab04f1281c9a1f1061a9e57c7121b28fbcd25e0 /include | |
| parent | 9399e05e65aae282679c86a15abe6df7a7d736cb (diff) | |
[PATCH] Fix IP checksum for SuSE 9.0 compiler
The hammer branch based gcc 3.3 in SuSE 9.0 has a more aggressive
optimizer. ip_send_check has this code:
iph->check = 0;
iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
The new gcc optimizes the first store away because it doesn't know
that ip_fast_csum reads its input memory. This leads to occassionally
packets with wrong IP header checksum getting sent; this happens especially
with NFS. Fixing it in the constraints would have been ugly and probably
not future proof, so this patch just adds a memory clobber to ip_fast_csum.
For some reason the issue only hits in 2.6, we haven't seen it in 2.4.
Problem occurs on both i386 and x86-64.
Credit goes to Olaf Kirch for tracking this down.
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-i386/checksum.h | 3 | ||||
| -rw-r--r-- | include/asm-x86_64/checksum.h | 3 |
2 files changed, 4 insertions, 2 deletions
diff --git a/include/asm-i386/checksum.h b/include/asm-i386/checksum.h index 15d7909bfe3c..1afe056aa3cd 100644 --- a/include/asm-i386/checksum.h +++ b/include/asm-i386/checksum.h @@ -83,7 +83,8 @@ static inline unsigned short ip_fast_csum(unsigned char * iph, are modified, we must also specify them as outputs, or gcc will assume they contain their original values. */ : "=r" (sum), "=r" (iph), "=r" (ihl) - : "1" (iph), "2" (ihl)); + : "1" (iph), "2" (ihl) + : "memory"); return(sum); } diff --git a/include/asm-x86_64/checksum.h b/include/asm-x86_64/checksum.h index 35d3e37d9378..3718a8fbbc21 100644 --- a/include/asm-x86_64/checksum.h +++ b/include/asm-x86_64/checksum.h @@ -68,7 +68,8 @@ static inline unsigned short ip_fast_csum(unsigned char *iph, unsigned int ihl) are modified, we must also specify them as outputs, or gcc will assume they contain their original values. */ : "=r" (sum), "=r" (iph), "=r" (ihl) - : "1" (iph), "2" (ihl)); + : "1" (iph), "2" (ihl) + : "memory"); return(sum); } |