From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, ast@kernel.org,
daniel@iogearbox.net, kernel-team@fb.com,
john.fastabend@gmail.com, kpsingh@chromium.org
Subject: Re: [PATCH v2 bpf-next 1/4] perf: export get/put_chain_entry()
Date: Fri, 26 Jun 2020 13:00:46 +0200 [thread overview]
Message-ID: <20200626110046.GB4817@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200626001332.1554603-2-songliubraving@fb.com>
On Thu, Jun 25, 2020 at 05:13:29PM -0700, Song Liu wrote:
> This would be used by bpf stack mapo.
Would it make sense to sanitize the API a little before exposing it?
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 334d48b16c36..016894b0d2c2 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -159,8 +159,10 @@ static struct perf_callchain_entry *get_callchain_entry(int *rctx)
return NULL;
entries = rcu_dereference(callchain_cpus_entries);
- if (!entries)
+ if (!entries) {
+ put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
return NULL;
+ }
cpu = smp_processor_id();
@@ -183,12 +185,9 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
int rctx;
entry = get_callchain_entry(&rctx);
- if (rctx == -1)
+ if (!entry || rctx == -1)
return NULL;
- if (!entry)
- goto exit_put;
-
ctx.entry = entry;
ctx.max_stack = max_stack;
ctx.nr = entry->nr = init_nr;
next prev parent reply other threads:[~2020-06-26 11:01 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-26 0:13 [PATCH v2 bpf-next 0/4] bpf: introduce bpf_get_task_stack() Song Liu
2020-06-26 0:13 ` [PATCH v2 bpf-next 1/4] perf: export get/put_chain_entry() Song Liu
2020-06-26 11:00 ` Peter Zijlstra [this message]
2020-06-26 20:06 ` Andrii Nakryiko
2020-06-26 21:38 ` Song Liu
2020-06-26 21:29 ` Song Liu
2020-06-26 0:13 ` [PATCH v2 bpf-next 2/4] bpf: introduce helper bpf_get_task_stak() Song Liu
2020-06-26 15:40 ` Yonghong Song
2020-06-26 22:37 ` Song Liu
2020-06-26 20:17 ` Andrii Nakryiko
2020-06-26 20:22 ` Andrii Nakryiko
2020-06-26 22:45 ` Song Liu
2020-06-26 22:51 ` Andrii Nakryiko
2020-06-26 23:47 ` Song Liu
2020-06-27 0:06 ` Andrii Nakryiko
2020-06-26 0:13 ` [PATCH v2 bpf-next 3/4] bpf: allow %pB in bpf_seq_printf() and bpf_trace_printk() Song Liu
2020-06-26 15:44 ` [Potential Spoof] " Yonghong Song
2020-06-26 0:13 ` [PATCH v2 bpf-next 4/4] selftests/bpf: add bpf_iter test with bpf_get_task_stack() Song Liu
2020-06-26 15:52 ` Yonghong Song
2020-06-26 20:21 ` Andrii Nakryiko
2020-06-26 23:05 ` Song Liu
2020-06-26 23:11 ` Andrii Nakryiko
2020-06-26 23:40 ` Song Liu
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