Hi, Arnd
On 12/05/2015 12:44 AM, Arnd Bergmann wrote:
On Friday 04 December 2015 23:11:58 Bamvor Jian Zhang wrote:
diff --git a/drivers/char/lp.c b/drivers/char/lp.c index c4094c4..a207e0c 100644 --- a/drivers/char/lp.c +++ b/drivers/char/lp.c @@ -136,6 +136,14 @@ #include <asm/irq.h> #include <asm/uaccess.h> +/*
- FIXME: It should be removed after COMPAT_USE_64BIT_TIME is accessible for
- 32bit architecture.
- */
+#ifndef COMPAT_USE_64BIT_TIME +#define COMPAT_USE_64BIT_TIME (0) +#endif /* COMPAT_USE_64BIT_TIME */
Unfortunately, I think this can't work: the kernel has no idea whether user space uses a 32-bit or 64-bit time_t, and we need to be able to support both kinds of user space at the same time.
What we have to do instead is change the definition of LPSETTIMEOUT, like
#if __BITS_PER_SIZE_T >= __BITS_PER_LONG #define LPSETTIMEOUT 0x060f /* set parport timeout */ #else #define LPSETTIMEOUT _IOW(0x06, 0x0f, struct timeval) #endif
We need to decide what the correct #if condition should be, but the idea is that all current user space remains unchanged, while user space built with a 64-bit time_t sees the modified definition of LPSETTIMEOUT and passes that into the kernel when using the larger structure.
/* if you have more than 8 printers, remember to increase LP_NO */ #define LP_NO 8 @@ -572,6 +580,22 @@ static int lp_release(struct inode * inode, struct file * file) return 0; } +static int lp_set_timeout(unsigned int minor, s64 tv_sec, s64 tv_usec)
tv_usec does not need to be 64-bit here, it has to be below 1 million.
Oh, yes. I will update in my next version.
+{
- long to_jiffies;
- if ((tv_sec < 0) || (tv_usec < 0))
return -EINVAL;- to_jiffies = usecs_to_jiffies(tv_usec);
- to_jiffies += tv_sec * (long)HZ;
- if (to_jiffies <= 0)
return -EINVAL;- lp_table[minor].timeout = to_jiffies;
- return 0;
+}
I think tv_sec can also be shorter, as we ignore the upper bits after the multiplication with HZ.
Given that long is 64bit in 64bit architecture, shall I keep tv_sec as s64 and cast HZ to s64 as well? + to_jiffies += tv_sec * (s64)HZ;
Regards
Bamvor
Arnd