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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: "Haibo Xu (Arm Technology China)" <Haibo.Xu@arm.com>,
	Steve Capper <Steve.Capper@arm.com>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	"jdike@addtoit.com" <jdike@addtoit.com>,
	"x86@kernel.org" <x86@kernel.org>,
	Will Deacon <Will.Deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Richard Weinberger <richard@nod.at>,
	Ingo Molnar <mingo@redhat.com>, Paul Mackerras <paulus@samba.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Bin Lu (Arm Technology China)" <Bin.Lu@arm.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/6] ptrace: introduce ptrace_syscall_enter to consolidate PTRACE_SYSEMU handling
Date: Mon, 4 Mar 2019 06:23:32 -0600	[thread overview]
Message-ID: <20190304122331.GG3969@gate.crashing.org> (raw)
In-Reply-To: <20190304104643.GA28643@e107155-lin>

On Mon, Mar 04, 2019 at 10:46:43AM +0000, Sudeep Holla wrote:
> On Mon, Mar 04, 2019 at 08:03:47AM +0000, Haibo Xu (Arm Technology China) wrote:
> > On 2019/3/1 2:32, Sudeep Holla wrote:
> > > +long ptrace_syscall_enter(struct pt_regs *regs)
> > > +{
> > > +#ifdef TIF_SYSCALL_EMU
> > > +	if (test_thread_flag(TIF_SYSCALL_EMU)) {
> > > +		if (tracehook_report_syscall_entry(regs));
> > 
> > Shall we remove the semi-colon at end of the above line?
> 
> Added intentionally to keep GCC happy.

GCC warns because the user explicitly asked for it, with __must_check.
If you want to do things with an "if" like this, you should write e.g.

		if (tracehook_report_syscall_entry(regs))
			/*
			 * We can ignore the return code here, because of
			 * X and Y and Z.
			 */
			;

Or it probably is nicer to use a block:

		if (tracehook_report_syscall_entry(regs)) {
			/*
			 * We can ignore the return code here, because of
			 * X and Y and Z.
			 */
		}

The point is, you *always* should have a nice fat comment if you are
ignoring the return code of a __must_check function.


Segher

  reply	other threads:[~2019-03-04 12:25 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-28 18:32 [PATCH 0/6] ptrace: consolidate PTRACE_SYSEMU handling and add support for arm64 Sudeep Holla
2019-02-28 18:32 ` [PATCH 1/6] ptrace: move clearing of TIF_SYSCALL_EMU flag to core Sudeep Holla
2019-02-28 18:32 ` [PATCH 2/6] ptrace: introduce ptrace_syscall_enter to consolidate PTRACE_SYSEMU handling Sudeep Holla
2019-03-04  8:03   ` Haibo Xu (Arm Technology China)
2019-03-04 10:46     ` Sudeep Holla
2019-03-04 12:23       ` Segher Boessenkool [this message]
2019-03-04 12:27         ` Sudeep Holla
2019-02-28 18:32 ` [PATCH 3/6] x86: clean up _TIF_SYSCALL_EMU handling using ptrace_syscall_enter hook Sudeep Holla
2019-03-03  1:11   ` Andy Lutomirski
2019-03-04 10:07     ` Sudeep Holla
2019-03-04  8:25   ` Haibo Xu (Arm Technology China)
2019-03-04 10:12     ` Sudeep Holla
2019-03-05  2:14       ` Haibo Xu (Arm Technology China)
2019-03-11 18:34         ` Sudeep Holla
2019-03-12  1:34           ` Haibo Xu (Arm Technology China)
2019-03-12  3:04             ` Andy Lutomirski
2019-03-12 12:09               ` Sudeep Holla
2019-03-13  1:03                 ` Haibo Xu (Arm Technology China)
2019-03-14 10:51                   ` Sudeep Holla
2019-03-15  5:48                     ` Haibo Xu (Arm Technology China)
2019-03-12 12:05             ` Sudeep Holla
2019-02-28 18:32 ` [PATCH 4/6] powerpc: use common ptrace_syscall_enter hook to handle _TIF_SYSCALL_EMU Sudeep Holla
2019-03-04  9:36   ` Haibo Xu (Arm Technology China)
2019-03-04 10:42     ` Sudeep Holla
2019-02-28 18:32 ` [PATCH 5/6] arm64: add PTRACE_SYSEMU{,SINGLESTEP} definations to uapi headers Sudeep Holla
2019-02-28 18:32 ` [PATCH 6/6] arm64: ptrace: add support for syscall emulation Sudeep Holla

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