From: Arnd Bergmann <arnd@kernel.org>
To: Bailey Forrest <bcf@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH net] gve: DQO: Suppress unused var warnings
Date: Tue, 28 Sep 2021 16:15:06 +0200 [thread overview]
Message-ID: <CAK8P3a1P9ZGBCub2s62OjrUa1Hwk66zHHESEj06MPY8qwjK7Ag@mail.gmail.com> (raw)
In-Reply-To: <CANH7hM4Y2gt9PW_1oZbMQfvT6Bih9U-Ckt7d-w4fKkLp2R-rKA@mail.gmail.com>
On Tue, Sep 28, 2021 at 2:00 AM Bailey Forrest <bcf@google.com> wrote:
> On Mon, Sep 27, 2021 at 4:21 PM Jakub Kicinski <kuba@kernel.org> wrote:
> > On Mon, 27 Sep 2021 13:21:30 -0700 Bailey Forrest wrote:
> >
> > Looks like fixing this on the wrong end, dma_unmap_len_set()
> > and friends should always evaluate their arguments.
>
> That makes sense.
>
> Arnd, if you want to fix this inside of the dma_* macros, the
> following diff resolves the errors reported for this driver:
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index dca2b1355bb1..f51eee0f678e 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -590,10 +590,21 @@ static inline int dma_mmap_wc(struct device *dev,
> #else
> #define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME)
> #define DEFINE_DMA_UNMAP_LEN(LEN_NAME)
> -#define dma_unmap_addr(PTR, ADDR_NAME) (0)
> -#define dma_unmap_addr_set(PTR, ADDR_NAME, VAL) do { } while (0)
> -#define dma_unmap_len(PTR, LEN_NAME) (0)
> -#define dma_unmap_len_set(PTR, LEN_NAME, VAL) do { } while (0)
> +
> +#define dma_unmap_addr(PTR, ADDR_NAME) ({ (void)PTR; 0; })
> +
> +#define dma_unmap_addr_set(PTR, ADDR_NAME, VAL) do { \
Unfortunately, this breaks every other driver using these macros, as the
point of them is that the unmap-address is not actually defined
and not taking up space in data structure. Referencing it by name
is a compile-time bug.
I've come up with a new patch to gve that just removes the
"struct gve_tx_dma_buf" and open-codes the access everywhere,
sending that as v2 now. Feel free to take that and modify as needed
before sending on, or doing yet another patch.
Arnd
next prev parent reply other threads:[~2021-09-28 14:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 23:19 [PATCH net] gve: DQO: Suppress unused var warnings Bailey Forrest
2021-09-27 9:58 ` Arnd Bergmann
2021-09-27 20:21 ` Bailey Forrest
2021-09-27 23:21 ` Jakub Kicinski
2021-09-27 23:59 ` Bailey Forrest
2021-09-28 14:15 ` Arnd Bergmann [this message]
2021-09-28 20:04 ` Bailey Forrest
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