Mark switch cases where we are expecting to fall through.
This patch fixes the following warning (Building: powerpc):
drivers/macintosh/smu.c: In function 'smu_queue_i2c':
drivers/macintosh/smu.c:854:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
cmd->info.devaddr &= 0xfe;
~~~~~~~~~~~~~~~~~~^~~~~~~
drivers/macintosh/smu.c:855:2: note: here
case SMU_I2C_TRANSFER_STDSUB:
^~~~
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Gustavo A. R. Silva <[email protected]>
Cc: Kees Cook <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
---
drivers/macintosh/smu.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
index 276065c888bc..23f1f41c8602 100644
--- a/drivers/macintosh/smu.c
+++ b/drivers/macintosh/smu.c
@@ -852,6 +852,7 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd)
break;
case SMU_I2C_TRANSFER_COMBINED:
cmd->info.devaddr &= 0xfe;
+ /* fall through */
case SMU_I2C_TRANSFER_STDSUB:
if (cmd->info.sublen > 3)
return -EINVAL;
--
2.22.0
--
Cheers,
Stephen Rothwell
Hi all,
On Tue, 30 Jul 2019 14:37:04 +1000 Stephen Rothwell <[email protected]> wrote:
>
> Mark switch cases where we are expecting to fall through.
>
> This patch fixes the following warning (Building: powerpc):
>
> drivers/macintosh/smu.c: In function 'smu_queue_i2c':
> drivers/macintosh/smu.c:854:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
> cmd->info.devaddr &= 0xfe;
> ~~~~~~~~~~~~~~~~~~^~~~~~~
> drivers/macintosh/smu.c:855:2: note: here
> case SMU_I2C_TRANSFER_STDSUB:
> ^~~~
>
> Cc: Benjamin Herrenschmidt <[email protected]>
> Cc: Gustavo A. R. Silva <[email protected]>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Stephen Rothwell <[email protected]>
Fixes: 0365ba7fb1fa ("[PATCH] ppc64: SMU driver update & i2c support")
Sorry, forgot :-)
--
Cheers,
Stephen Rothwell
Stephen Rothwell <[email protected]> writes:
> Mark switch cases where we are expecting to fall through.
>
> This patch fixes the following warning (Building: powerpc):
>
> drivers/macintosh/smu.c: In function 'smu_queue_i2c':
> drivers/macintosh/smu.c:854:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
> cmd->info.devaddr &= 0xfe;
> ~~~~~~~~~~~~~~~~~~^~~~~~~
> drivers/macintosh/smu.c:855:2: note: here
> case SMU_I2C_TRANSFER_STDSUB:
> ^~~~
>
> Cc: Benjamin Herrenschmidt <[email protected]>
> Cc: Gustavo A. R. Silva <[email protected]>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Stephen Rothwell <[email protected]>
> ---
> drivers/macintosh/smu.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
> index 276065c888bc..23f1f41c8602 100644
> --- a/drivers/macintosh/smu.c
> +++ b/drivers/macintosh/smu.c
> @@ -852,6 +852,7 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd)
> break;
> case SMU_I2C_TRANSFER_COMBINED:
> cmd->info.devaddr &= 0xfe;
> + /* fall through */
> case SMU_I2C_TRANSFER_STDSUB:
> if (cmd->info.sublen > 3)
> return -EINVAL;
Why do we think it's an expected fall through? I can't really convince
myself from the surrounding code that it's definitely intentional.
cheers
Hi Michael,
On Wed, 31 Jul 2019 00:28:55 +1000 Michael Ellerman <[email protected]> wrote:
>
> Why do we think it's an expected fall through? I can't really convince
> myself from the surrounding code that it's definitely intentional.
Its been that way since this code was introduced by commit
0365ba7fb1fa ("[PATCH] ppc64: SMU driver update & i2c support")
in 2005 ...
--
Cheers,
Stephen Rothwell
On Wed, Jul 31, 2019 at 12:28:55AM +1000, Michael Ellerman wrote:
> Stephen Rothwell <[email protected]> writes:
> > Mark switch cases where we are expecting to fall through.
> >
> > This patch fixes the following warning (Building: powerpc):
> >
> > drivers/macintosh/smu.c: In function 'smu_queue_i2c':
> > drivers/macintosh/smu.c:854:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
> > cmd->info.devaddr &= 0xfe;
> > ~~~~~~~~~~~~~~~~~~^~~~~~~
> > drivers/macintosh/smu.c:855:2: note: here
> > case SMU_I2C_TRANSFER_STDSUB:
> > ^~~~
> >
> > Cc: Benjamin Herrenschmidt <[email protected]>
> > Cc: Gustavo A. R. Silva <[email protected]>
> > Cc: Kees Cook <[email protected]>
> > Signed-off-by: Stephen Rothwell <[email protected]>
> > ---
> > drivers/macintosh/smu.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
> > index 276065c888bc..23f1f41c8602 100644
> > --- a/drivers/macintosh/smu.c
> > +++ b/drivers/macintosh/smu.c
> > @@ -852,6 +852,7 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd)
> > break;
> > case SMU_I2C_TRANSFER_COMBINED:
> > cmd->info.devaddr &= 0xfe;
> > + /* fall through */
> > case SMU_I2C_TRANSFER_STDSUB:
> > if (cmd->info.sublen > 3)
> > return -EINVAL;
>
> Why do we think it's an expected fall through? I can't really convince
> myself from the surrounding code that it's definitely intentional.
Yeah, good question. Just now when I went looking for who
used SMU_I2C_TRANSFER_COMBINED, I found the only caller in
arch/powerpc/platforms/powermac/low_i2c.c and it is clearly using a
fall-through for building the command for "stdsub" and "combined",
so I think that's justification enough:
switch(bus->mode) {
case pmac_i2c_mode_std:
if (subsize != 0)
return -EINVAL;
cmd->info.type = SMU_I2C_TRANSFER_SIMPLE;
break;
case pmac_i2c_mode_stdsub:
case pmac_i2c_mode_combined:
if (subsize > 3 || subsize < 1)
return -EINVAL;
cmd->info.sublen = subsize;
/* that's big-endian only but heh ! */
memcpy(&cmd->info.subaddr, ((char *)&subaddr) + (4 - subsize),
subsize);
if (bus->mode == pmac_i2c_mode_stdsub)
cmd->info.type = SMU_I2C_TRANSFER_STDSUB;
else
cmd->info.type = SMU_I2C_TRANSFER_COMBINED;
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On Tue, 2019-07-30 at 10:07 -0700, Kees Cook wrote:
>
> > Why do we think it's an expected fall through? I can't really
> > convince
> > myself from the surrounding code that it's definitely intentional.
>
> Yeah, good question. Just now when I went looking for who
> used SMU_I2C_TRANSFER_COMBINED, I found the only caller in
> arch/powerpc/platforms/powermac/low_i2c.c and it is clearly using a
> fall-through for building the command for "stdsub" and "combined",
> so I think that's justification enough:
Yes, sorry for the delay, the fall through is intentional.
Cheers,
Ben.
Kees Cook <[email protected]> writes:
> On Wed, Jul 31, 2019 at 12:28:55AM +1000, Michael Ellerman wrote:
>> Stephen Rothwell <[email protected]> writes:
>> > Mark switch cases where we are expecting to fall through.
>> >
>> > This patch fixes the following warning (Building: powerpc):
>> >
>> > drivers/macintosh/smu.c: In function 'smu_queue_i2c':
>> > drivers/macintosh/smu.c:854:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> > cmd->info.devaddr &= 0xfe;
>> > ~~~~~~~~~~~~~~~~~~^~~~~~~
>> > drivers/macintosh/smu.c:855:2: note: here
>> > case SMU_I2C_TRANSFER_STDSUB:
>> > ^~~~
>> >
>> > Cc: Benjamin Herrenschmidt <[email protected]>
>> > Cc: Gustavo A. R. Silva <[email protected]>
>> > Cc: Kees Cook <[email protected]>
>> > Signed-off-by: Stephen Rothwell <[email protected]>
>> > ---
>> > drivers/macintosh/smu.c | 1 +
>> > 1 file changed, 1 insertion(+)
>> >
>> > diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
>> > index 276065c888bc..23f1f41c8602 100644
>> > --- a/drivers/macintosh/smu.c
>> > +++ b/drivers/macintosh/smu.c
>> > @@ -852,6 +852,7 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd)
>> > break;
>> > case SMU_I2C_TRANSFER_COMBINED:
>> > cmd->info.devaddr &= 0xfe;
>> > + /* fall through */
>> > case SMU_I2C_TRANSFER_STDSUB:
>> > if (cmd->info.sublen > 3)
>> > return -EINVAL;
>>
>> Why do we think it's an expected fall through? I can't really convince
>> myself from the surrounding code that it's definitely intentional.
>
> Yeah, good question. Just now when I went looking for who
> used SMU_I2C_TRANSFER_COMBINED, I found the only caller in
> arch/powerpc/platforms/powermac/low_i2c.c and it is clearly using a
> fall-through for building the command for "stdsub" and "combined",
> so I think that's justification enough:
>
> switch(bus->mode) {
> case pmac_i2c_mode_std:
> if (subsize != 0)
> return -EINVAL;
> cmd->info.type = SMU_I2C_TRANSFER_SIMPLE;
> break;
> case pmac_i2c_mode_stdsub:
> case pmac_i2c_mode_combined:
> if (subsize > 3 || subsize < 1)
> return -EINVAL;
> cmd->info.sublen = subsize;
> /* that's big-endian only but heh ! */
> memcpy(&cmd->info.subaddr, ((char *)&subaddr) + (4 - subsize),
> subsize);
> if (bus->mode == pmac_i2c_mode_stdsub)
> cmd->info.type = SMU_I2C_TRANSFER_STDSUB;
> else
> cmd->info.type = SMU_I2C_TRANSFER_COMBINED;
>
>
> Reviewed-by: Kees Cook <[email protected]>
Thanks.
cheers
On Tue, 2019-07-30 at 04:37:04 UTC, Stephen Rothwell wrote:
> Mark switch cases where we are expecting to fall through.
>
> This patch fixes the following warning (Building: powerpc):
>
> drivers/macintosh/smu.c: In function 'smu_queue_i2c':
> drivers/macintosh/smu.c:854:21: warning: this statement may fall through [-=
> Wimplicit-fallthrough=3D]
> cmd->info.devaddr &=3D 0xfe;
> ~~~~~~~~~~~~~~~~~~^~~~~~~
> drivers/macintosh/smu.c:855:2: note: here
> case SMU_I2C_TRANSFER_STDSUB:
> ^~~~
>
> Cc: Benjamin Herrenschmidt <[email protected]>
> Cc: Gustavo A. R. Silva <[email protected]>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Stephen Rothwell <[email protected]>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/7440ea8b2a4430eef5120d0a7faac6c39304ae6d
cheers