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From: Joel Stanley <joel@jms.id.au>
Date: Wed, 7 Jun 2017 21:30:31 +0930
Message-ID: <CACPK8XcLBdLijc-CfxoFRNq6pHX6nGri7JCTyfJS9qx+8Juv=Q@mail.gmail.com>
Subject: Re: [PATCH kmod] util: fix non-static assert_cc use
To: linux-modules@vger.kernel.org
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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On Wed, Jun 7, 2017 at 3:48 PM, Joel Stanley <joel@jms.id.au> wrote:
> In commit a6ede6c7ad46 (util: fix warning of equal values on logical OR)
> the runtime check for EAGAIN and EWOULDBLOCK being equal was converted
> into an assert.
>
> For the case where the compiler supports _Static_assert, this is can be
> called staticly. However the fallback for older compilers uses a
> non-static test that needs to be called from a function context.
>
> Move the assert into the functions that used to have the runtime check.
> The test does not add any runtime overhead, so it is fine to duplicate
> it.
>
> Tested with and without HAVE_STATIC_ASSERT defined using GCC 6.3.
>
> Signed-off-by: Joel Stanley <joel@jms.id.au>

I just saw the git history and noticed that Thomas sent a patch fixing
this already. Excellent! Sorry for the noise.

Cheers,

Joel

> ---
>  shared/util.c              | 4 ++--
>  testsuite/test-testsuite.c | 1 +
>  2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/shared/util.c b/shared/util.c
> index 9de080aabb18..c402953b4699 100644
> --- a/shared/util.c
> +++ b/shared/util.c
> @@ -49,8 +49,6 @@ static const struct kmod_ext {
>         { }
>  };
>
> -assert_cc(EAGAIN == EWOULDBLOCK);
> -
>  /* string handling functions and memory allocations                         */
>  /* ************************************************************************ */
>
> @@ -200,6 +198,7 @@ ssize_t read_str_safe(int fd, char *buf, size_t buflen)
>  {
>         size_t todo = buflen - 1;
>         size_t done = 0;
> +       assert_cc(EAGAIN == EWOULDBLOCK);
>
>         do {
>                 ssize_t r = read(fd, buf + done, todo);
> @@ -225,6 +224,7 @@ ssize_t write_str_safe(int fd, const char *buf, size_t buflen)
>  {
>         size_t todo = buflen;
>         size_t done = 0;
> +       assert_cc(EAGAIN == EWOULDBLOCK);
>
>         do {
>                 ssize_t r = write(fd, buf + done, todo);
> diff --git a/testsuite/test-testsuite.c b/testsuite/test-testsuite.c
> index 56e73609f204..5bafc6551a23 100644
> --- a/testsuite/test-testsuite.c
> +++ b/testsuite/test-testsuite.c
> @@ -88,6 +88,7 @@ static int testsuite_rootfs_open(const struct test *t)
>  {
>         char buf[100];
>         int fd, done;
> +       assert_cc(EAGAIN == EWOULDBLOCK);
>
>         fd = open("/lib/modules/a", O_RDONLY);
>         if (fd < 0)
> --
> 2.11.0
>