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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-06-24 04:04:38 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-06-29 10:24:29 +0400 |
| commit | b6b3ecc71a0664d44ed8d087d583aee98fbf492a (patch) | |
| tree | 078e92d78578d3a8833dd225f71a6b2a982ea5be /include/linux/u64_stats_sync.h | |
| parent | a095cfc40ec7ebe63e9532383c5b5c2a27b14075 (diff) | |
| download | linux-b6b3ecc71a0664d44ed8d087d583aee98fbf492a.tar.xz | |
net: u64_stats_sync improvements
- Add a comment about interrupts:
6) If counter might be written by an interrupt, readers should block
interrupts.
- Fix a typo in sample of use.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/u64_stats_sync.h')
| -rw-r--r-- | include/linux/u64_stats_sync.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h index d0505156ed52..b38e3a58de83 100644 --- a/include/linux/u64_stats_sync.h +++ b/include/linux/u64_stats_sync.h @@ -23,6 +23,10 @@ * pure reads. But if they have to fetch many values, it's better to not allow * preemptions/interruptions to avoid many retries. * + * 6) If counter might be written by an interrupt, readers should block interrupts. + * (On UP, there is no seqcount_t protection, a reader allowing interrupts could + * read partial values) + * * Usage : * * Stats producer (writer) should use following template granted it already got @@ -46,7 +50,7 @@ * start = u64_stats_fetch_begin(&stats->syncp); * tbytes = stats->bytes64; // non atomic operation * tpackets = stats->packets64; // non atomic operation - * } while (u64_stats_fetch_retry(&stats->lock, syncp)); + * } while (u64_stats_fetch_retry(&stats->syncp, start)); * * * Example of use in drivers/net/loopback.c, using per_cpu containers, |