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| author | Hou Tao <houtao1@huawei.com> | 2025-02-20 12:22:59 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-10 14:37:30 +0200 |
| commit | 43681d603ff0c6caa919d5b7569bf8ed32f8e055 (patch) | |
| tree | c0efce6031bc2f9fd39306e15556c544b14ba993 /kernel | |
| parent | 8e3e21129cfe2e6b516b167a880bdc6e2d63b18c (diff) | |
| download | linux-43681d603ff0c6caa919d5b7569bf8ed32f8e055.tar.gz linux-43681d603ff0c6caa919d5b7569bf8ed32f8e055.tar.bz2 linux-43681d603ff0c6caa919d5b7569bf8ed32f8e055.zip | |
bpf: Use preempt_count() directly in bpf_send_signal_common()
[ Upstream commit b4a8b5bba712a711d8ca1f7d04646db63f9c88f5 ]
bpf_send_signal_common() uses preemptible() to check whether or not the
current context is preemptible. If it is preemptible, it will use
irq_work to send the signal asynchronously instead of trying to hold a
spin-lock, because spin-lock is sleepable under PREEMPT_RT.
However, preemptible() depends on CONFIG_PREEMPT_COUNT. When
CONFIG_PREEMPT_COUNT is turned off (e.g., CONFIG_PREEMPT_VOLUNTARY=y),
!preemptible() will be evaluated as 1 and bpf_send_signal_common() will
use irq_work unconditionally.
Fix it by unfolding "!preemptible()" and using "preempt_count() != 0 ||
irqs_disabled()" instead.
Fixes: 87c544108b61 ("bpf: Send signals asynchronously if !preemptible")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250220042259.1583319-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 9d8f60e0cb55..545393601be8 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -853,7 +853,7 @@ static int bpf_send_signal_common(u32 sig, enum pid_type type) if (unlikely(is_global_init(current))) return -EPERM; - if (!preemptible()) { + if (preempt_count() != 0 || irqs_disabled()) { /* Do an early check on signal validity. Otherwise, * the error is lost in deferred irq_work. */ |