Messages in this thread | | | Date | Fri, 11 Jul 2014 17:06:30 -0500 | From | Brian W Hart <> | Subject | Re: [PATCH] cpufreq: make table sentinal macros unsigned to match use |
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On Mon, Jun 30, 2014 at 10:25:20AM +0530, Viresh Kumar wrote: > On 28 June 2014 02:39, Brian W Hart <hartb@linux.vnet.ibm.com> wrote: > > Commit 5eeaf1f18973 (cpufreq: Fix build error on some platforms that > > use cpufreq_for_each_*) moved function cpufreq_next_valid() to a public > > header. Warnings are now generated when objects including that header > > are built with -Wsign-compare (as an out-of-tree module might be): > > > > .../include/linux/cpufreq.h: In function ‘cpufreq_next_valid’: > > .../include/linux/cpufreq.h:519:27: warning: comparison between signed > > and unsigned integer expressions [-Wsign-compare] > > while ((*pos)->frequency != CPUFREQ_TABLE_END) > > ^ > > .../include/linux/cpufreq.h:520:25: warning: comparison between signed > > and unsigned integer expressions [-Wsign-compare] > > if ((*pos)->frequency != CPUFREQ_ENTRY_INVALID) > > ^ > > > > Constants CPUFREQ_ENTRY_INVALID and CPUFREQ_TABLE_END are signed, but > > are used with unsigned member 'frequency' of cpufreq_frequency_table. > > Update the macro definitions to be explicitly unsigned to match their > > use. > > > > This also corrects potentially wrong behavior of clk_rate_table_iter() > > if unsigned long is wider than usigned int. > > > > Signed-off-by: Brian W Hart <hartb@linux.vnet.ibm.com> > > --- > > These macros are fairly broadly used in the kernel so I was bit leery > > of changing them, but after inspection I think it's fine. I found 102 > > uses of the macros, of which: > > > > 99 are uses with cpufreq_frequency_table.frequency (95) or with local > > variables of the same type as frequency (4). These should be just > > fine with this change--we're just making explicit a conversion that > > was previously implicit. > > > > 2 are uses with a local variable of different type (unsigned long) than > > 'frequency' (in drivers/sh/clk/core.c). One of these uses is safe; > > the other (in clk_rate_table_iter()) is broken if unsigned long > > is wider than unsigned int. As a side-effect, this patch corrects > > the potential misbehavior there. > > > > 1 is a use in macro cpufreq_for_each_entry() with what _should_ be the > > frequency member of a cpufreq_frequency_table, provided the caller it > > well-behaved. There are 18 callers of this macro; all are well-behaved. > > So these should also be safe. > > I would have moved some of it to logs, they look good. > > > include/linux/cpufreq.h | 4 ++-- > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > > index ec4112d..8f8ae95 100644 > > --- a/include/linux/cpufreq.h > > +++ b/include/linux/cpufreq.h > > @@ -482,8 +482,8 @@ extern struct cpufreq_governor cpufreq_gov_conservative; > > *********************************************************************/ > > > > /* Special Values of .frequency field */ > > -#define CPUFREQ_ENTRY_INVALID ~0 > > -#define CPUFREQ_TABLE_END ~1 > > +#define CPUFREQ_ENTRY_INVALID ~0u > > +#define CPUFREQ_TABLE_END ~1u > > /* Special Values of .flags field */ > > #define CPUFREQ_BOOST_FREQ (1 << 0) > > Thanks. > > Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
I haven't seen this appear in the linux-pm tree yet. Is there anything further needed on my part--aside from patience?
Thank you, brian
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