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Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Nick Desaulniers Subject: Re: [PATCH] x86/hw_breakpoints: Return -EINVAL in default case in hw_breakpoint_arch_parse Message-ID: <20190320191057.GD28744@archlinux-ryzen> References: <20190307212756.4648-1-natechancellor@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190307212756.4648-1-natechancellor@gmail.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 07, 2019 at 02:27:56PM -0700, Nathan Chancellor wrote: > When building with -Wsometimes-uninitialized, Clang warns: > > arch/x86/kernel/hw_breakpoint.c:355:2: warning: variable 'align' is used > uninitialized whenever switch default is taken > [-Wsometimes-uninitialized] > > It's not wrong but we can see that arch_build_bp_info will only ever > initialize hw->len to one of the specified switch cases. We can easily > silence Clang by just returning -EINVAL in the default case so that we > can never use align without initializing it first. > > Link: https://github.com/ClangBuiltLinux/linux/issues/392 > Suggested-by: Nick Desaulniers > Signed-off-by: Nathan Chancellor > --- > arch/x86/kernel/hw_breakpoint.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c > index ff9bfd40429e..d73083021002 100644 > --- a/arch/x86/kernel/hw_breakpoint.c > +++ b/arch/x86/kernel/hw_breakpoint.c > @@ -354,6 +354,7 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, > #endif > default: > WARN_ON_ONCE(1); > + return -EINVAL; > } > > /* > -- > 2.21.0 > Gentle ping (if there was a response to this, I didn't receive it). I know I sent it in the middle of a merge window so I get if it slipped through the cracks. Thanks, Nathan