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| author |   Eric Dumazet <edumazet@google.com> | 2021-10-26 14:41:33 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2021-10-27 11:13:52 -0700 |
| commit | 61a0abaee2092eee69e44fe60336aa2f5b578938 (patch) | |
| tree | 5ee181827d5064079aaa77ce0e3523a70daf1e86 /kernel/bpf | |
| parent | bpf: Fixes possible race in update_prog_stats() for 32bit arches (diff) | |
| download | linux-dev-61a0abaee2092eee69e44fe60336aa2f5b578938.tar.xz linux-dev-61a0abaee2092eee69e44fe60336aa2f5b578938.zip | |
bpf: Use u64_stats_t in struct bpf_prog_stats
Commit 316580b69d0a ("u64_stats: provide u64_stats_t type")
fixed possible load/store tearing on 64bit arches.
For instance the following C code
stats->nsecs += sched_clock() - start;
Could be rightfully implemented like this by a compiler,
confusing concurrent readers a lot:
stats->nsecs += sched_clock();
// arbitrary delay
stats->nsecs -= start;
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211026214133.3114279-4-eric.dumazet@gmail.com
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/syscall.c | 18 | ||||
| -rw-r--r-- | kernel/bpf/trampoline.c | 6 |
2 files changed, 15 insertions, 9 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 5beb321b3b3b..3e1c024ce3ed 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1804,8 +1804,14 @@ static int bpf_prog_release(struct inode *inode, struct file *filp) return 0; } +struct bpf_prog_kstats { + u64 nsecs; + u64 cnt; + u64 misses; +}; + static void bpf_prog_get_stats(const struct bpf_prog *prog, - struct bpf_prog_stats *stats) + struct bpf_prog_kstats *stats) { u64 nsecs = 0, cnt = 0, misses = 0; int cpu; @@ -1818,9 +1824,9 @@ static void bpf_prog_get_stats(const struct bpf_prog *prog, st = per_cpu_ptr(prog->stats, cpu); do { start = u64_stats_fetch_begin_irq(&st->syncp); - tnsecs = st->nsecs; - tcnt = st->cnt; - tmisses = st->misses; + tnsecs = u64_stats_read(&st->nsecs); + tcnt = u64_stats_read(&st->cnt); + tmisses = u64_stats_read(&st->misses); } while (u64_stats_fetch_retry_irq(&st->syncp, start)); nsecs += tnsecs; cnt += tcnt; @@ -1836,7 +1842,7 @@ static void bpf_prog_show_fdinfo(struct seq_file *m, struct file *filp) { const struct bpf_prog *prog = filp->private_data; char prog_tag[sizeof(prog->tag) * 2 + 1] = { }; - struct bpf_prog_stats stats; + struct bpf_prog_kstats stats; bpf_prog_get_stats(prog, &stats); bin2hex(prog_tag, prog->tag, sizeof(prog->tag)); @@ -3577,7 +3583,7 @@ static int bpf_prog_get_info_by_fd(struct file *file, struct bpf_prog_info __user *uinfo = u64_to_user_ptr(attr->info.info); struct bpf_prog_info info; u32 info_len = attr->info.info_len; - struct bpf_prog_stats stats; + struct bpf_prog_kstats stats; char __user *uinsns; u32 ulen; int err; diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index e5963de368ed..e98de5e73ba5 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -545,7 +545,7 @@ static void notrace inc_misses_counter(struct bpf_prog *prog) stats = this_cpu_ptr(prog->stats); u64_stats_update_begin(&stats->syncp); - stats->misses++; + u64_stats_inc(&stats->misses); u64_stats_update_end(&stats->syncp); } @@ -590,8 +590,8 @@ static void notrace update_prog_stats(struct bpf_prog *prog, stats = this_cpu_ptr(prog->stats); flags = u64_stats_update_begin_irqsave(&stats->syncp); - stats->cnt++; - stats->nsecs += sched_clock() - start; + u64_stats_inc(&stats->cnt); + u64_stats_add(&stats->nsecs, sched_clock() - start); u64_stats_update_end_irqrestore(&stats->syncp, flags); } } |