On Mon, Jun 30, 2014 at 10:25:20AM +0530, Viresh Kumar wrote:

On 28 June 2014 02:39, Brian W Hart [off-list ref] wrote:

quoted

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 <redacted>
---
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.

quoted

 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