2014-01-30 11:50:07

by Dan Carpenter

Subject: [patch] hw_random: cleanup in hwrng_register()

My static checker complains that:

drivers/char/hw_random/core.c:341 hwrng_register()
warn: we tested 'old_rng' before and it was 'false'

The problem is that sometimes we test "if (!old_rng)" and sometimes we
test "if (must_register_misc)". The static checker knows they are
equivalent but a human being reading the code could easily be confused.

I have simplified the code by removing the "must_register_misc" variable
and I have removed the redundant check on "if (!old_rng)".

Signed-off-by: Dan Carpenter <[email protected]>

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index b9495a8c05c6..463382036a01 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -301,7 +301,6 @@ err_misc_dereg:

int hwrng_register(struct hwrng *rng)
{
- int must_register_misc;
int err = -EINVAL;
struct hwrng *old_rng, *tmp;

@@ -326,7 +325,6 @@ int hwrng_register(struct hwrng *rng)
goto out_unlock;
}

- must_register_misc = (current_rng == NULL);
old_rng = current_rng;
if (!old_rng) {
err = hwrng_init(rng);
@@ -335,13 +333,11 @@ int hwrng_register(struct hwrng *rng)
current_rng = rng;
}
err = 0;
- if (must_register_misc) {
+ if (!old_rng) {
err = register_miscdev();
if (err) {
- if (!old_rng) {
- hwrng_cleanup(rng);
- current_rng = NULL;
- }
+ hwrng_cleanup(rng);
+ current_rng = NULL;
goto out_unlock;
}
}

2014-02-01 08:06:12

by Rusty Russell

Subject: Re: [patch] hw_random: cleanup in hwrng_register()

Dan Carpenter <[email protected]> writes:
> My static checker complains that:
>
> drivers/char/hw_random/core.c:341 hwrng_register()
> warn: we tested 'old_rng' before and it was 'false'
>
> The problem is that sometimes we test "if (!old_rng)" and sometimes we
> test "if (must_register_misc)". The static checker knows they are
> equivalent but a human being reading the code could easily be confused.
>
> I have simplified the code by removing the "must_register_misc" variable
> and I have removed the redundant check on "if (!old_rng)".
>
> Signed-off-by: Dan Carpenter <[email protected]>

Yeah, clearer too.

Reviewed-by: Rusty Russell <[email protected]>

Thanks,
Rusty.

>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index b9495a8c05c6..463382036a01 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -301,7 +301,6 @@ err_misc_dereg:
>
> int hwrng_register(struct hwrng *rng)
> {
> - int must_register_misc;
> int err = -EINVAL;
> struct hwrng *old_rng, *tmp;
>
> @@ -326,7 +325,6 @@ int hwrng_register(struct hwrng *rng)
> goto out_unlock;
> }
>
> - must_register_misc = (current_rng == NULL);
> old_rng = current_rng;
> if (!old_rng) {
> err = hwrng_init(rng);
> @@ -335,13 +333,11 @@ int hwrng_register(struct hwrng *rng)
> current_rng = rng;
> }
> err = 0;
> - if (must_register_misc) {
> + if (!old_rng) {
> err = register_miscdev();
> if (err) {
> - if (!old_rng) {
> - hwrng_cleanup(rng);
> - current_rng = NULL;
> - }
> + hwrng_cleanup(rng);
> + current_rng = NULL;
> goto out_unlock;
> }
> }

2014-02-09 09:22:46

by Herbert Xu

Subject: Re: [patch] hw_random: cleanup in hwrng_register()

On Fri, Jan 31, 2014 at 04:18:51PM +1030, Rusty Russell wrote:
> Dan Carpenter <[email protected]> writes:
> > My static checker complains that:
> >
> > drivers/char/hw_random/core.c:341 hwrng_register()
> > warn: we tested 'old_rng' before and it was 'false'
> >
> > The problem is that sometimes we test "if (!old_rng)" and sometimes we
> > test "if (must_register_misc)". The static checker knows they are
> > equivalent but a human being reading the code could easily be confused.
> >
> > I have simplified the code by removing the "must_register_misc" variable
> > and I have removed the redundant check on "if (!old_rng)".
> >
> > Signed-off-by: Dan Carpenter <[email protected]>
>
> Yeah, clearer too.
>
> Reviewed-by: Rusty Russell <[email protected]>

Patch applied.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt