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bpf: Fix bpf_put_raw_tracepoint()'s use of __module_address()

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__module_address() needs to be called with preemption disabled or with
module_mutex taken. preempt_disable() is enough for read-only uses, which is
what this fix does. Also, module_put() does internal check for NULL, so drop
it as well.

Fixes: a38d1107f937 ("bpf: support raw tracepoints in modules")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-2-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2020-12-03 12:46:21 -08:00 committed by Alexei Starovoitov
parent cadd64807c
commit 12cc126df8
1 changed files with 5 additions and 3 deletions
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8
kernel/trace/bpf_trace.c
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@ -2060,10 +2060,12 @@ struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name)
void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp) void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
{ {
struct module *mod = __module_address((unsigned long)btp); struct module *mod;
if (mod) preempt_disable();
module_put(mod); mod = __module_address((unsigned long)btp);
module_put(mod);
preempt_enable();
} }
static __always_inline static __always_inline