diff options
| author | Andrew Morton <akpm@osdl.org> | 2006-02-11 17:55:52 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-02-11 21:41:11 -0800 |
| commit | 643a654540579b0dcc7a206a4a7475276a41aff0 (patch) | |
| tree | e31d40e4362e4dc7823b7290c0de2a9353d3d117 /fs/select.c | |
| parent | 33042a9ff4d126ba944b9dc3076665a2029e0a34 (diff) | |
| download | lwn-643a654540579b0dcc7a206a4a7475276a41aff0.tar.gz lwn-643a654540579b0dcc7a206a4a7475276a41aff0.zip | |
[PATCH] select: fix returned timeval
With David Woodhouse <dwmw2@infradead.org>
select() presently has a habit of increasing the value of the user's
`timeout' argument on return.
We were writing back a timeout larger than the original. We _deliberately_
round up, since we know we must wait at _least_ as long as the caller asks
us to.
The patch adds a couple of helper functions for magnitude comparison of
timespecs and of timevals, and uses them to prevent the various poll and
select functions from returning a timeout which is larger than the one which
was passed in.
The patch also fixes a bug in compat_sys_pselect7(): it was adding the new
timeout value to the old one and was returning that. It should just return
the new timeout value.
(We have various handy timespec/timeval-to-from-nsec conversion functions in
time.h. But this code open-codes it all).
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@muc.de>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: george anzinger <george@mvista.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/select.c')
| -rw-r--r-- | fs/select.c | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/fs/select.c b/fs/select.c index bc60a3e14ef3..6ce68a9c8976 100644 --- a/fs/select.c +++ b/fs/select.c @@ -398,11 +398,15 @@ asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp, ret = core_sys_select(n, inp, outp, exp, &timeout); if (tvp) { + struct timeval rtv; + if (current->personality & STICKY_TIMEOUTS) goto sticky; - tv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); - tv.tv_sec = timeout; - if (copy_to_user(tvp, &tv, sizeof(tv))) { + rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); + rtv.tv_sec = timeout; + if (timeval_compare(&rtv, &tv) < 0) + rtv = tv; + if (copy_to_user(tvp, &rtv, sizeof(rtv))) { sticky: /* * If an application puts its timeval in read-only @@ -460,11 +464,16 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp, ret = core_sys_select(n, inp, outp, exp, &timeout); if (tsp) { + struct timespec rts; + if (current->personality & STICKY_TIMEOUTS) goto sticky; - ts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * 1000; - ts.tv_sec = timeout; - if (copy_to_user(tsp, &ts, sizeof(ts))) { + rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * + 1000; + rts.tv_sec = timeout; + if (timespec_compare(&rts, &ts) < 0) + rts = ts; + if (copy_to_user(tsp, &rts, sizeof(rts))) { sticky: /* * If an application puts its timeval in read-only @@ -758,12 +767,17 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds, sigprocmask(SIG_SETMASK, &sigsaved, NULL); if (tsp && timeout >= 0) { + struct timespec rts; + if (current->personality & STICKY_TIMEOUTS) goto sticky; /* Yes, we know it's actually an s64, but it's also positive. */ - ts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * 1000; - ts.tv_sec = timeout; - if (copy_to_user(tsp, &ts, sizeof(ts))) { + rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * + 1000; + rts.tv_sec = timeout; + if (timespec_compare(&rts, &ts) < 0) + rts = ts; + if (copy_to_user(tsp, &rts, sizeof(rts))) { sticky: /* * If an application puts its timeval in read-only |