path: root/tools
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authorJosh Wu <>2015-09-16 18:21:04 +0800
committerTom Rini <>2015-09-28 10:48:25 -0400
commit3e4dad50320d20894710276eb09f2057c6985065 (patch)
tree4561fc6d676581095dd65fd2ef8ace4cdd7b5091 /tools
parent1090a56c87121e740ba3fcac89739f7bd6c9ac66 (diff)
tools: gen_eth_addr: add getpid() to time(0) to avoid duplicated seed
As 'time(0) | getpid()' will have a lot of duplicated value. It is not a expected behavior. We expect different value for the seed when when run it in many times. So this patch will left shift the getpid() and add to time(0). That avoid duplicated value. Test command is like: % RUN=0; while [ $RUN -lt 10000 ]; do tools/gen_eth_addr; RUN=$(($RUN+1)); done | sort | uniq | wc -l 10000 This patch is incorporated with suggestions made by Wolfgang Denk and Andreas Bießmann. Thanks them a lot. Signed-off-by: Josh Wu <> Acked-by: Andreas Bießmann <> Acked-by: Wolfgang Denk <> Tested-by: Wolfgang Denk <>
Diffstat (limited to 'tools')
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/gen_eth_addr.c b/tools/gen_eth_addr.c
index bf9d935efd..5fa3e0cf56 100644
--- a/tools/gen_eth_addr.c
+++ b/tools/gen_eth_addr.c
@@ -15,7 +15,7 @@ main(int argc, char *argv[])
unsigned long ethaddr_low, ethaddr_high;
- srand(time(0) | getpid());
+ srand(time(0) + (getpid() << 8));
* setting the 2nd LSB in the most significant byte of
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