netdev - Re: [PATCH] net: stmmac: Avoid one more sometimes uninitialized Clang warning

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Message-Id: <20190308.232057.1297154950610356905.davem@davemloft.net>
Date:   Fri, 08 Mar 2019 23:20:57 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     natechancellor@...il.com
Cc:     peppe.cavallaro@...com, alexandre.torgue@...com,
        joabreu@...opsys.com, mcoquelin.stm32@...il.com,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com, ndesaulniers@...gle.com
Subject: Re: [PATCH] net: stmmac: Avoid one more sometimes uninitialized
 Clang warning

From: Nathan Chancellor <natechancellor@...il.com>
Date: Thu,  7 Mar 2019 21:02:39 -0700

> When building with -Wsometimes-uninitialized, Clang warns:
> 
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
> 'ns' is used uninitialized whenever 'if' condition is false
> [-Werror,-Wsometimes-uninitialized]
> drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c:111:2: error: variable
> 'ns' is used uninitialized whenever '&&' condition is false
> [-Werror,-Wsometimes-uninitialized]
> 
> Clang is concerned with the use of stmmac_do_void_callback (which
> stmmac_get_systime wraps), as it may fail to initialize these values if
> the if condition was ever false (meaning the callback doesn't exist).
> It's not wrong because the callback is what initializes ns. While it's
> unlikely that the callback is going to disappear at some point and make
> that condition false, we can easily avoid this warning by zero
> initializing the variable.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/384
> Fixes: df103170854e ("net: stmmac: Avoid sometimes uninitialized Clang warnings")
> Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

Applied, thanks Nathan.