2016-03-22 09:55:38

by Tina Ruchandani

Subject: [PATCH] prism54: isl_38xx: Replace 'struct timeval'

'struct timeval' uses a 32-bit seconds field which will overflow in
year 2038 and beyond. This patch is part of a larger effort to remove
all instances of 'struct timeval' from the kernel and replace them
with 64-bit timekeeping variables.
The correctness of the code isn't affected by this patch - the seconds
value being printed would earlier be wrong due to overflow in timeval,
and now it gets truncated to 32-bit due to the 'long' cast used on
tv.sec field to prevent compiler warnings. Truly fixing this would
require changing the debug print to print more than 8 digits and using
a different specifier from %li.
The patch was build-tested / debugged by removing the
"if VERBOSE > SHOW_ERROR_MESSAGES" guards.

Signed-off-by: Tina Ruchandani <[email protected]>
---
drivers/net/wireless/intersil/prism54/isl_38xx.c | 29 +++++++++++++++---------
1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/net/wireless/intersil/prism54/isl_38xx.c b/drivers/net/wireless/intersil/prism54/isl_38xx.c
index 333c1a2..e510375 100644
--- a/drivers/net/wireless/intersil/prism54/isl_38xx.c
+++ b/drivers/net/wireless/intersil/prism54/isl_38xx.c
@@ -19,6 +19,7 @@
#include <linux/module.h>
#include <linux/types.h>
#include <linux/delay.h>
+#include <linux/ktime.h>

#include <asm/uaccess.h>
#include <asm/io.h>
@@ -113,7 +114,7 @@ isl38xx_trigger_device(int asleep, void __iomem *device_base)

#if VERBOSE > SHOW_ERROR_MESSAGES
u32 counter = 0;
- struct timeval current_time;
+ struct timespec64 current_ts64;
DEBUG(SHOW_FUNCTION_CALLS, "isl38xx trigger device\n");
#endif

@@ -121,22 +122,25 @@ isl38xx_trigger_device(int asleep, void __iomem *device_base)
if (asleep) {
/* device is in powersave, trigger the device for wakeup */
#if VERBOSE > SHOW_ERROR_MESSAGES
- do_gettimeofday(&current_time);
+ ktime_get_real_ts64(&current_ts64);
DEBUG(SHOW_TRACING, "%08li.%08li Device wakeup triggered\n",
- current_time.tv_sec, (long)current_time.tv_usec);
+ (long)current_ts64.tv_sec,
+ (long)(current_ts64.tv_nsec / NSEC_PER_USEC));

DEBUG(SHOW_TRACING, "%08li.%08li Device register read %08x\n",
- current_time.tv_sec, (long)current_time.tv_usec,
+ (long)current_ts64.tv_sec,
+ (long)(current_ts64.tv_nsec / NSEC_PER_USEC),
readl(device_base + ISL38XX_CTRL_STAT_REG));
#endif

reg = readl(device_base + ISL38XX_INT_IDENT_REG);
if (reg == 0xabadface) {
#if VERBOSE > SHOW_ERROR_MESSAGES
- do_gettimeofday(&current_time);
+ ktime_get_real_ts64(&current_ts64);
DEBUG(SHOW_TRACING,
"%08li.%08li Device register abadface\n",
- current_time.tv_sec, (long)current_time.tv_usec);
+ (long)current_ts64.tv_sec,
+ (long)(current_ts64.tv_nsec / NSEC_PER_USEC));
#endif
/* read the Device Status Register until Sleepmode bit is set */
while (reg = readl(device_base + ISL38XX_CTRL_STAT_REG),
@@ -150,12 +154,14 @@ isl38xx_trigger_device(int asleep, void __iomem *device_base)
#if VERBOSE > SHOW_ERROR_MESSAGES
DEBUG(SHOW_TRACING,
"%08li.%08li Device register read %08x\n",
- current_time.tv_sec, (long)current_time.tv_usec,
+ (long)current_ts64.tv_sec,
+ (long)(current_ts64.tv_nsec / NSEC_PER_USEC),
readl(device_base + ISL38XX_CTRL_STAT_REG));
- do_gettimeofday(&current_time);
+ ktime_get_real_ts64(&current_ts64);
DEBUG(SHOW_TRACING,
"%08li.%08li Device asleep counter %i\n",
- current_time.tv_sec, (long)current_time.tv_usec,
+ (long)current_ts64.tv_sec,
+ (long)(current_ts64.tv_nsec / NSEC_PER_USEC),
counter);
#endif
}
@@ -168,9 +174,10 @@ isl38xx_trigger_device(int asleep, void __iomem *device_base)

/* perform another read on the Device Status Register */
reg = readl(device_base + ISL38XX_CTRL_STAT_REG);
- do_gettimeofday(&current_time);
+ ktime_get_real_ts64(&current_ts64);
DEBUG(SHOW_TRACING, "%08li.%08li Device register read %08x\n",
- current_time.tv_sec, (long)current_time.tv_usec, reg);
+ (long)current_ts64.tv_sec,
+ (long)(current_ts64.tv_nsec / NSEC_PER_USEC), reg);
#endif
} else {
/* device is (still) awake */
--
2.8.0.rc3.226.g39d4020

2016-03-22 11:51:35

by Arnd Bergmann

Subject: Re: [Y2038] [PATCH] prism54: isl_38xx: Replace 'struct timeval'

On Tuesday 22 March 2016 02:55:22 Tina Ruchandani wrote:
> Truly fixing this would
> require changing the debug print to print more than 8 digits and using
> a different specifier from %li.

Why not just change it to %lli, and a cast to s64? I don't think the
format string or the number of digits is important here because it's just
debug output that is normally disabled.

I also see an existing bug in the format string: "%08li.%08li" means we
end up printing a six digit microsecond value with two leading zeros,
which is rather confusing. I think using "%lld.%06ld" would be best
here, or possibly "%lld.%09ld" to print the whole nanoseconds so we
can skip the division.

Arnd