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authorJianpeng Ma <majianpeng@gmail.com>2012-08-03 10:42:00 +0200
committerJens Axboe <axboe@kernel.dk>2012-08-03 10:42:00 +0200
commit0676806707281e27b13d44323bed580a8160b7a4 (patch)
treeff0a03f54a64ff9fc7b3e1bde13373164a1525e3 /block/genhd.c
parent85b9f66a41eb8ee3f1dfc95707412705463cdd97 (diff)
downloadkernel-0676806707281e27b13d44323bed580a8160b7a4.tar.gz
block: Don't use static to define "void *p" in show_partition_start()
I met a odd prblem:read /proc/partitions may return zero. I wrote a file test.c: int main() { char buff[4096]; int ret; int fd; printf("pid=%d\n",getpid()); while (1) { fd = open("/proc/partitions", O_RDONLY); if (fd < 0) { printf("open error %s\n", strerror(errno)); return 0; } ret = read(fd, buff, 4096); if (ret <= 0) printf("ret=%d, %s, %ld\n", ret, strerror(errno), lseek(fd,0,SEEK_CUR)); close(fd); } exit(0); } You can reproduce by: 1:while true;do cat /proc/partitions > /dev/null ;done 2:./test I reviewed the code and found: >> static void *show_partition_start(struct seq_file *seqf, loff_t *pos) >> { >> static void *p; >> >> p = disk_seqf_start(seqf, pos); >> if (!IS_ERR_OR_NULL(p) && !*pos) >> seq_puts(seqf, "major minor #blocks name\n\n"); >> return p; >> } test cat /proc/partitions p = disk_seqf_start()(Not NULL) p = disk_seqf_start()(NULL because pos) if (!IS_ERR_OR_NULL(p) && !*pos) Signed-off-by: Jianpeng Ma <majianpeng@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/genhd.c')
-rw-r--r--block/genhd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/block/genhd.c b/block/genhd.c
index cac7366957c3..d839723303c8 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -835,7 +835,7 @@ static void disk_seqf_stop(struct seq_file *seqf, void *v)
static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
{
- static void *p;
+ void *p;
p = disk_seqf_start(seqf, pos);
if (!IS_ERR_OR_NULL(p) && !*pos)