From: David Miller <davem@davemloft.net>
To: natechancellor@gmail.com
Cc: peppe.cavallaro@st.com, alexandre.torgue@st.com,
joabreu@synopsys.com, mcoquelin.stm32@gmail.com,
netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
ndesaulniers@google.com
Subject: Re: [PATCH v2] net: stmmac: Avoid sometimes uninitialized Clang warnings
Date: Thu, 07 Mar 2019 10:59:38 -0800 (PST) [thread overview]
Message-ID: <20190307.105938.496464522338008986.davem@davemloft.net> (raw)
In-Reply-To: <20190307180027.6226-1-natechancellor@gmail.com>
From: Nathan Chancellor <natechancellor@gmail.com>
Date: Thu, 7 Mar 2019 11:00:28 -0700
> When building with -Wsometimes-uninitialized, Clang warns:
>
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:495:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:532:3: warning: variable 'ns' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c:741:3: warning: variable 'sec_inc' is used uninitialized whenever '&&' condition is false [-Wsometimes-uninitialized]
>
> Clang is concerned with the use of stmmac_do_void_callback (which
> stmmac_get_timestamp and stmmac_config_sub_second_increment wrap),
> as it may fail to initialize these values if the if condition was ever
> false (meaning the callbacks don't exist). It's not wrong because the
> callbacks (get_timestamp and config_sub_second_increment respectively)
> are the ones that initialize the variables. While it's unlikely that the
> callbacks are ever going to disappear and make that condition false, we
> can easily avoid this warning by zero initialize the variables.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/384
> Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Applied.
next prev parent reply other threads:[~2019-03-07 18:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-07 16:21 [PATCH] net: stmmac: Avoid sometimes uninitialized Clang warnings Nathan Chancellor
2019-03-07 17:49 ` David Miller
2019-03-07 17:54 ` Nick Desaulniers
2019-03-07 18:00 ` [PATCH v2] " Nathan Chancellor
2019-03-07 18:12 ` Nick Desaulniers
2019-03-07 18:59 ` David Miller [this message]
2019-03-08 4:02 ` [PATCH] net: stmmac: Avoid one more sometimes uninitialized Clang warning Nathan Chancellor
2019-03-08 21:02 ` Nick Desaulniers
2019-03-09 7:20 ` David Miller
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