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bpf: Fix possible race in inc_misses_counter 

It seems inc_misses_counter() suffers from same issue fixed in
the commit d979617aa8 ("bpf: Fixes possible race in update_prog_stats()
for 32bit arches"):
As it can run while interrupts are enabled, it could
be re-entered and the u64_stats syncp could be mangled.

Fixes: 9ed9e9ba23 ("bpf: Count the number of times recursion was prevented")
Signed-off-by: He Fengqing <hefengqing@huawei.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20220122102936.1219518-1-hefengqing@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
He Fengqing 2022-01-22 10:29:36 +00:00 committed by Alexei Starovoitov
parent 63ee956f69
commit 0e3135d3bf
1 changed files with 3 additions and 2 deletions
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5
kernel/bpf/trampoline.c
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@ -550,11 +550,12 @@ static __always_inline u64 notrace bpf_prog_start_time(void)
static void notrace inc_misses_counter(struct bpf_prog *prog)
{
struct bpf_prog_stats *stats;
unsigned int flags;
stats = this_cpu_ptr(prog->stats);
u64_stats_update_begin(&stats->syncp);
flags = u64_stats_update_begin_irqsave(&stats->syncp);
u64_stats_inc(&stats->misses);
u64_stats_update_end(&stats->syncp);
u64_stats_update_end_irqrestore(&stats->syncp, flags);
}
/* The logic is similar to bpf_prog_run(), but with an explicit