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Fri, 26 Jun 2020 21:29:38 +0000 From: Song Liu To: Peter Zijlstra CC: bpf , Networking , linux-kernel , Alexei Starovoitov , Daniel Borkmann , Kernel Team , john fastabend , "kpsingh@chromium.org" Subject: Re: [PATCH v2 bpf-next 1/4] perf: export get/put_chain_entry() Thread-Topic: [PATCH v2 bpf-next 1/4] perf: export get/put_chain_entry() Thread-Index: AQHWS06t5H2BZnsAuEuKRuZX7jQ17qjqu3gAgACvs4A= Date: Fri, 26 Jun 2020 21:29:38 +0000 Message-ID: <6A3C511C-4749-4672-988C-AA8149FB6355@fb.com> References: <20200626001332.1554603-1-songliubraving@fb.com> <20200626001332.1554603-2-songliubraving@fb.com> <20200626110046.GB4817@hirez.programming.kicks-ass.net> In-Reply-To: <20200626110046.GB4817@hirez.programming.kicks-ass.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.80.23.2.2) authentication-results: infradead.org; dkim=none (message not signed) header.d=none;infradead.org; dmarc=none action=none header.from=fb.com; 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I will fold this in the next version.=20 Thanks, Song >=20 > 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_en= try(int *rctx) > return NULL; >=20 > entries =3D rcu_dereference(callchain_cpus_entries); > - if (!entries) > + if (!entries) { > + put_recursion_context(this_cpu_ptr(callchain_recursion), rctx); > return NULL; > + } >=20 > cpu =3D smp_processor_id(); >=20 > @@ -183,12 +185,9 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr= , bool kernel, bool user, > int rctx; >=20 > entry =3D get_callchain_entry(&rctx); > - if (rctx =3D=3D -1) > + if (!entry || rctx =3D=3D -1) > return NULL; >=20 > - if (!entry) > - goto exit_put; > - > ctx.entry =3D entry; > ctx.max_stack =3D max_stack; > ctx.nr =3D entry->nr =3D init_nr;