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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>,
	"open list:BPF (Safe dynamic programs and tools)" 
	<bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
	"acme@kernel.org" <acme@kernel.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"kjain@linux.ibm.com" <kjain@linux.ibm.com>,
	Kernel Team <Kernel-team@fb.com>,
	jbaron@akamai.com, rostedt@goodmis.org, ardb@kernel.org
Subject: Re: [PATCH v2 bpf-next 1/3] perf: enable branch record for software events
Date: Sat, 4 Sep 2021 16:01:13 -0700	[thread overview]
Message-ID: <20210904230113.cpjota2sttx2w7aa@treble> (raw)
In-Reply-To: <YS+0eIeAJsRRArk4@hirez.programming.kicks-ass.net>

On Wed, Sep 01, 2021 at 07:12:24PM +0200, Peter Zijlstra wrote:
> On Mon, Aug 30, 2021 at 08:07:24PM +0200, Peter Zijlstra wrote:
> > On Mon, Aug 30, 2021 at 05:41:46PM +0000, Song Liu wrote:
> > > DECLARE_STATIC_CALL(perf_snapshot_branch_stack,
> > >                    int (*)(struct perf_branch_snapshot *));
> > 
> > > Something like 
> > > 
> > > typedef int (perf_snapshot_branch_stack_t)(struct perf_branch_snapshot *);
> > > DECLARE_STATIC_CALL(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t);
> > > 
> > > seems to work fine. 
> > 
> > Oh urg, indeed. It wants a function type, not a function pointer type.
> > I've been bitten by that before. Go with the typedef, that's the sanest.
> 
> The below is the best I can make of it... it's a little inconsistent and
> somewhat tricky, but at least the compiler yells hard if you get it
> wrong.
> 
> I can *almost* get to: DEFINE_STATIC_CALL(foo, &func), except for
> ARCH_DEFINE_STATIC_CALL_TRAMP() which needs the actual function name
> string for the ASM :-(
> 
> The rest can do with a function pointer type and have it work.

Seems reasonable to me.

-- 
Josh


  reply	other threads:[~2021-09-04 23:01 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 22:13 [PATCH v2 bpf-next 0/3] bpf: introduce bpf_get_branch_snapshot Song Liu
2021-08-26 22:13 ` [PATCH v2 bpf-next 1/3] perf: enable branch record for software events Song Liu
2021-08-30 10:22   ` Peter Zijlstra
2021-08-30 15:25     ` Song Liu
2021-08-30 16:06       ` Peter Zijlstra
2021-08-30 16:36         ` Song Liu
2021-09-01 17:09           ` Peter Zijlstra
2021-08-30 17:41     ` Song Liu
2021-08-30 18:07       ` Peter Zijlstra
2021-09-01 17:12         ` Peter Zijlstra
2021-09-04 23:01           ` Josh Poimboeuf [this message]
2021-08-30 10:43   ` Peter Zijlstra
2021-08-30 16:06     ` Song Liu
2021-08-26 22:13 ` [PATCH v2 bpf-next 2/3] bpf: introduce helper bpf_get_branch_snapshot Song Liu
2021-08-27  9:28   ` kernel test robot
2021-08-27 15:10   ` kernel test robot
2021-08-30 10:47     ` Peter Zijlstra
2021-08-26 22:13 ` [PATCH v2 bpf-next 3/3] selftests/bpf: add test for bpf_get_branch_snapshot Song Liu

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