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ptp: reduce stack usage when measuring the system time offset 

This patch removes the large buffer from the stack of the system
offset ioctl and replaces it with a kmalloced buffer.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Richard Cochran 2012-11-26 01:44:35 +00:00 committed by David S. Miller
parent c7ec0badcc
commit c3484c275d
1 changed files with 14 additions and 7 deletions
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21
drivers/ptp/ptp_chardev.c
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@ -34,7 +34,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
{ {
struct ptp_clock_caps caps; struct ptp_clock_caps caps;
struct ptp_clock_request req; struct ptp_clock_request req;
struct ptp_sys_offset sysoff; struct ptp_sys_offset *sysoff = NULL;
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock); struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
struct ptp_clock_info *ops = ptp->info; struct ptp_clock_info *ops = ptp->info;
struct ptp_clock_time *pct; struct ptp_clock_time *pct;
@ -94,17 +94,22 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
break; break;
case PTP_SYS_OFFSET: case PTP_SYS_OFFSET:
if (copy_from_user(&sysoff, (void __user *)arg, sysoff = kmalloc(sizeof(*sysoff), GFP_KERNEL);
sizeof(sysoff))) { if (!sysoff) {
err = -ENOMEM;
break;
}
if (copy_from_user(sysoff, (void __user *)arg,
sizeof(*sysoff))) {
err = -EFAULT; err = -EFAULT;
break; break;
} }
if (sysoff.n_samples > PTP_MAX_SAMPLES) { if (sysoff->n_samples > PTP_MAX_SAMPLES) {
err = -EINVAL; err = -EINVAL;
break; break;
} }
pct = &sysoff.ts[0]; pct = &sysoff->ts[0];
for (i = 0; i < sysoff.n_samples; i++) { for (i = 0; i < sysoff->n_samples; i++) {
getnstimeofday(&ts); getnstimeofday(&ts);
pct->sec = ts.tv_sec; pct->sec = ts.tv_sec;
pct->nsec = ts.tv_nsec; pct->nsec = ts.tv_nsec;
@ -117,7 +122,7 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
getnstimeofday(&ts); getnstimeofday(&ts);
pct->sec = ts.tv_sec; pct->sec = ts.tv_sec;
pct->nsec = ts.tv_nsec; pct->nsec = ts.tv_nsec;
if (copy_to_user((void __user *)arg, &sysoff, sizeof(sysoff))) if (copy_to_user((void __user *)arg, sysoff, sizeof(*sysoff)))
err = -EFAULT; err = -EFAULT;
break; break;
@ -125,6 +130,8 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
err = -ENOTTY; err = -ENOTTY;
break; break;
} }
kfree(sysoff);
return err; return err;
} }