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authorAndrew Morton <akpm@osdl.org>2006-02-11 17:55:52 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-11 21:41:11 -0800
commit643a654540579b0dcc7a206a4a7475276a41aff0 (patch)
treee31d40e4362e4dc7823b7290c0de2a9353d3d117 /fs/select.c
parent33042a9ff4d126ba944b9dc3076665a2029e0a34 (diff)
downloadlinux-linaro-stable-643a654540579b0dcc7a206a4a7475276a41aff0.tar.gz
[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.c32
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