From: Jiri Pirko <jiri@resnulli.us>
To: Petr Oros <poros@redhat.com>
Cc: netdev@vger.kernel.org, ivecera@redhat.com,
przemyslaw.kitszel@intel.com, horms@kernel.org,
Alexander Lobakin <aleksander.lobakin@intel.com>,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Tony Nguyen <anthony.l.nguyen@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Eric Joyner <eric.joyner@intel.com>,
Marcin Domagala <marcinx.domagala@intel.com>,
"moderated list:INTEL ETHERNET DRIVERS"
<intel-wired-lan@lists.osuosl.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net v3] ice: use proper macro for testing bit
Date: Tue, 18 Jun 2024 15:43:57 +0200 [thread overview]
Message-ID: <ZnGPHez662_8E7AA@nanopsycho.orion> (raw)
In-Reply-To: <20240618111119.721648-1-poros@redhat.com>
Tue, Jun 18, 2024 at 01:11:19PM CEST, poros@redhat.com wrote:
>Do not use _test_bit() macro for testing bit. The proper macro for this
>is one without underline.
>
>_test_bit() is what test_bit() was prior to const-optimization. It
>directly calls arch_test_bit(), i.e. the arch-specific implementation
>(or the generic one). It's strictly _internal_ and shouldn't be used
>anywhere outside the actual test_bit() macro.
>
>test_bit() is a wrapper which checks whether the bitmap and the bit
>number are compile-time constants and if so, it calls the optimized
>function which evaluates this call to a compile-time constant as well.
>If either of them is not a compile-time constant, it just calls _test_bit().
>test_bit() is the actual function to use anywhere in the kernel.
>
>IOW, calling _test_bit() avoids potential compile-time optimizations.
>
>The sensors is not a compile-time constant, thus most probably there
>are no object code changes before and after the patch.
>But anyway, we shouldn't call internal wrappers instead of
>the actual API.
>
>Fixes: 4da71a77fc3b ("ice: read internal temperature sensor")
>Acked-by: Ivan Vecera <ivecera@redhat.com>
>Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
>Signed-off-by: Petr Oros <poros@redhat.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
next prev parent reply other threads:[~2024-06-18 13:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-18 11:11 [PATCH net v3] ice: use proper macro for testing bit Petr Oros
2024-06-18 13:43 ` Jiri Pirko [this message]
2024-06-24 6:47 ` [Intel-wired-lan] " Pucha, HimasekharX Reddy
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