2021-12-27 13:07:40

by Qiang Wang

Subject: [PATCH v2 1/2] libbpf: Use probe_name for legacy kprobe

Fix a bug in commit 46ed5fc33db9, which wrongly used the
func_name instead of probe_name to register legacy kprobe.

Fixes: 46ed5fc33db9 ("libbpf: Refactor and simplify legacy kprobe code")
Reviewed-by: Hengqi Chen <[email protected]>
Tested-by: Hengqi Chen <[email protected]>
Co-developed-by: Chengming Zhou <[email protected]>
Signed-off-by: Qiang Wang <[email protected]>
Signed-off-by: Chengming Zhou <[email protected]>
---
tools/lib/bpf/libbpf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7c74342bb668..b7d6c951fa09 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9735,7 +9735,7 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name),
func_name, offset);

- legacy_probe = strdup(func_name);
+ legacy_probe = strdup(probe_name);
if (!legacy_probe)
return libbpf_err_ptr(-ENOMEM);

--
2.20.1

2021-12-27 13:07:45

by Qiang Wang

Subject: [PATCH v2 2/2] libbpf: Support repeated legacy kprobes on same function

If repeated legacy kprobes on same function in one process,
libbpf will register using the same probe name and got -EBUSY
error. So append index to the probe name format to fix this
problem.

Co-developed-by: Chengming Zhou <[email protected]>
Signed-off-by: Qiang Wang <[email protected]>
Signed-off-by: Chengming Zhou <[email protected]>
---
tools/lib/bpf/libbpf.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b7d6c951fa09..698e8864da02 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9634,7 +9634,10 @@ static int append_to_file(const char *file, const char *fmt, ...)
static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
const char *kfunc_name, size_t offset)
{
- snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), kfunc_name, offset);
+ static int index = 0;
+
+ snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset,
+ __sync_fetch_and_add(&index, 1));
}

static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
--
2.20.1

2022-01-05 23:40:26

by patchwork-bot+netdevbpf

Subject: Re: [PATCH v2 1/2] libbpf: Use probe_name for legacy kprobe

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <[email protected]>:

On Mon, 27 Dec 2021 21:07:12 +0800 you wrote:
> Fix a bug in commit 46ed5fc33db9, which wrongly used the
> func_name instead of probe_name to register legacy kprobe.
>
> Fixes: 46ed5fc33db9 ("libbpf: Refactor and simplify legacy kprobe code")
> Reviewed-by: Hengqi Chen <[email protected]>
> Tested-by: Hengqi Chen <[email protected]>
> Co-developed-by: Chengming Zhou <[email protected]>
> Signed-off-by: Qiang Wang <[email protected]>
> Signed-off-by: Chengming Zhou <[email protected]>
>
> [...]

Here is the summary with links:
- [v2,1/2] libbpf: Use probe_name for legacy kprobe
https://git.kernel.org/bpf/bpf-next/c/71cff670baff
- [v2,2/2] libbpf: Support repeated legacy kprobes on same function
https://git.kernel.org/bpf/bpf-next/c/51a33c60f1c2

You are awesome, thank you!
--
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