1 files changed, 223 insertions, 173 deletions

diff --git a/fs/select.c b/fs/select.c
index da0e88201c3a..448e44001286 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -24,9 +24,64 @@
 #include <linux/fdtable.h>
 #include <linux/fs.h>
 #include <linux/rcupdate.h>
+#include <linux/hrtimer.h>
 
 #include <asm/uaccess.h>
 
+
+/*
+ * Estimate expected accuracy in ns from a timeval.
+ *
+ * After quite a bit of churning around, we've settled on
+ * a simple thing of taking 0.1% of the timeout as the
+ * slack, with a cap of 100 msec.
+ * "nice" tasks get a 0.5% slack instead.
+ *
+ * Consider this comment an open invitation to come up with even
+ * better solutions..
+ */
+
+static long __estimate_accuracy(struct timespec *tv)
+{
+        long slack;
+        int divfactor = 1000;
+
+        if (task_nice(current) > 0)
+                divfactor = divfactor / 5;
+
+        slack = tv->tv_nsec / divfactor;
+        slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
+
+        if (slack > 100 * NSEC_PER_MSEC)
+                slack =  100 * NSEC_PER_MSEC;
+
+        if (slack < 0)
+                slack = 0;
+        return slack;
+}
+
+static long estimate_accuracy(struct timespec *tv)
+{
+        unsigned long ret;
+        struct timespec now;
+
+        /*
+         * Realtime tasks get a slack of 0 for obvious reasons.
+         */
+
+        if (rt_task(current))
+                return 0;
+
+        ktime_get_ts(&now);
+        now = timespec_sub(*tv, now);
+        ret = __estimate_accuracy(&now);
+        if (ret < current->timer_slack_ns)
+                return current->timer_slack_ns;
+        return ret;
+}
+
+
+
 struct poll_table_page {
         struct poll_table_page * next;
         struct poll_table_entry * entry;
@@ -130,6 +185,79 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
         add_wait_queue(wait_address, &entry->wait);
 }
 
+/**
+ * poll_select_set_timeout - helper function to setup the timeout value
+ * @to:         pointer to timespec variable for the final timeout
+ * @sec:        seconds (from user space)
+ * @nsec:       nanoseconds (from user space)
+ *
+ * Note, we do not use a timespec for the user space value here, That
+ * way we can use the function for timeval and compat interfaces as well.
+ *
+ * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
+ */
+int poll_select_set_timeout(struct timespec *to, long sec, long nsec)
+{
+        struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec};
+
+        if (!timespec_valid(&ts))
+                return -EINVAL;
+
+        /* Optimize for the zero timeout value here */
+        if (!sec && !nsec) {
+                to->tv_sec = to->tv_nsec = 0;
+        } else {
+                ktime_get_ts(to);
+                *to = timespec_add_safe(*to, ts);
+        }
+        return 0;
+}
+
+static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,
+                                      int timeval, int ret)
+{
+        struct timespec rts;
+        struct timeval rtv;
+
+        if (!p)
+                return ret;
+
+        if (current->personality & STICKY_TIMEOUTS)
+                goto sticky;
+
+        /* No update for zero timeout */
+        if (!end_time->tv_sec && !end_time->tv_nsec)
+                return ret;
+
+        ktime_get_ts(&rts);
+        rts = timespec_sub(*end_time, rts);
+        if (rts.tv_sec < 0)
+                rts.tv_sec = rts.tv_nsec = 0;
+
+        if (timeval) {
+                rtv.tv_sec = rts.tv_sec;
+                rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
+
+                if (!copy_to_user(p, &rtv, sizeof(rtv)))
+                        return ret;
+
+        } else if (!copy_to_user(p, &rts, sizeof(rts)))
+                return ret;
+
+        /*
+         * If an application puts its timeval in read-only memory, we
+         * don't want the Linux-specific update to the timeval to
+         * cause a fault after the select has completed
+         * successfully. However, because we're not updating the
+         * timeval, we can't restart the system call.
+         */
+
+sticky:
+        if (ret == -ERESTARTNOHAND)
+                ret = -EINTR;
+        return ret;
+}
+
 #define FDS_IN(fds, n)          (fds->in + n)
 #define FDS_OUT(fds, n)         (fds->out + n)
 #define FDS_EX(fds, n)          (fds->ex + n)
@@ -182,11 +310,13 @@ get_max:
 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
 #define POLLEX_SET (POLLPRI)
 
-int do_select(int n, fd_set_bits *fds, s64 *timeout)
+int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
 {
+        ktime_t expire, *to = NULL;
         struct poll_wqueues table;
         poll_table *wait;
-        int retval, i;
+        int retval, i, timed_out = 0;
+        unsigned long slack = 0;
 
         rcu_read_lock();
         retval = max_select_fd(n, fds);
@@ -198,12 +328,17 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
 
         poll_initwait(&table);
         wait = &table.pt;
-        if (!*timeout)
+        if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
                 wait = NULL;
+                timed_out = 1;
+        }
+
+        if (end_time && !timed_out)
+                slack = estimate_accuracy(end_time);
+
         retval = 0;
         for (;;) {
                 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
-                long __timeout;
 
                 set_current_state(TASK_INTERRUPTIBLE);
 
@@ -259,27 +394,25 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
                         cond_resched();
                 }
                 wait = NULL;
-                if (retval || !*timeout || signal_pending(current))
+                if (retval || timed_out || signal_pending(current))
                         break;
                 if (table.error) {
                         retval = table.error;
                         break;
                 }
 
-                if (*timeout < 0) {
-                        /* Wait indefinitely */
-                        __timeout = MAX_SCHEDULE_TIMEOUT;
-                } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT - 1)) {
-                        /* Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in a loop */
-                        __timeout = MAX_SCHEDULE_TIMEOUT - 1;
-                        *timeout -= __timeout;
-                } else {
-                        __timeout = *timeout;
-                        *timeout = 0;
+                /*
+                 * If this is the first loop and we have a timeout
+                 * given, then we convert to ktime_t and set the to
+                 * pointer to the expiry value.
+                 */
+                if (end_time && !to) {
+                        expire = timespec_to_ktime(*end_time);
+                        to = &expire;
                 }
-                __timeout = schedule_timeout(__timeout);
-                if (*timeout >= 0)
-                        *timeout += __timeout;
+
+                if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
+                        timed_out = 1;
         }
         __set_current_state(TASK_RUNNING);
 
@@ -300,7 +433,7 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
         ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
 
 int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
-                           fd_set __user *exp, s64 *timeout)
+                           fd_set __user *exp, struct timespec *end_time)
 {
         fd_set_bits fds;
         void *bits;
@@ -351,7 +484,7 @@ int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
         zero_fd_set(n, fds.res_out);
         zero_fd_set(n, fds.res_ex);
 
-        ret = do_select(n, &fds, timeout);
+        ret = do_select(n, &fds, end_time);
 
         if (ret < 0)
                 goto out;
@@ -377,7 +510,7 @@ out_nofds:
 asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
                         fd_set __user *exp, struct timeval __user *tvp)
 {
-        s64 timeout = -1;
+        struct timespec end_time, *to = NULL;
         struct timeval tv;
         int ret;
 
@@ -385,43 +518,14 @@ asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
                 if (copy_from_user(&tv, tvp, sizeof(tv)))
                         return -EFAULT;
 
-                if (tv.tv_sec < 0 || tv.tv_usec < 0)
+                to = &end_time;
+                if (poll_select_set_timeout(to, tv.tv_sec,
+                                            tv.tv_usec * NSEC_PER_USEC))
                         return -EINVAL;
-
-                /* Cast to u64 to make GCC stop complaining */
-                if ((u64)tv.tv_sec >= (u64)MAX_INT64_SECONDS)
-                        timeout = -1;   /* infinite */
-                else {
-                        timeout = DIV_ROUND_UP(tv.tv_usec, USEC_PER_SEC/HZ);
-                        timeout += tv.tv_sec * HZ;
-                }
         }
 
-        ret = core_sys_select(n, inp, outp, exp, &timeout);
-
-        if (tvp) {
-                struct timeval rtv;
-
-                if (current->personality & STICKY_TIMEOUTS)
-                        goto sticky;
-                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
-                         * memory, we don't want the Linux-specific update to
-                         * the timeval to cause a fault after the select has
-                         * completed successfully. However, because we're not
-                         * updating the timeval, we can't restart the system
-                         * call.
-                         */
-                        if (ret == -ERESTARTNOHAND)
-                                ret = -EINTR;
-                }
-        }
+        ret = core_sys_select(n, inp, outp, exp, to);
+        ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
 
         return ret;
 }
@@ -431,25 +535,17 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
                 fd_set __user *exp, struct timespec __user *tsp,
                 const sigset_t __user *sigmask, size_t sigsetsize)
 {
-        s64 timeout = MAX_SCHEDULE_TIMEOUT;
         sigset_t ksigmask, sigsaved;
-        struct timespec ts;
+        struct timespec ts, end_time, *to = NULL;
         int ret;
 
         if (tsp) {
                 if (copy_from_user(&ts, tsp, sizeof(ts)))
                         return -EFAULT;
 
-                if (ts.tv_sec < 0 || ts.tv_nsec < 0)
+                to = &end_time;
+                if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
                         return -EINVAL;
-
-                /* Cast to u64 to make GCC stop complaining */
-                if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS)
-                        timeout = -1;   /* infinite */
-                else {
-                        timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ);
-                        timeout += ts.tv_sec * HZ;
-                }
         }
 
         if (sigmask) {
@@ -463,32 +559,8 @@ asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
                 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
         }
 
-        ret = core_sys_select(n, inp, outp, exp, &timeout);
-
-        if (tsp) {
-                struct timespec rts;
-
-                if (current->personality & STICKY_TIMEOUTS)
-                        goto sticky;
-                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
-                         * memory, we don't want the Linux-specific update to
-                         * the timeval to cause a fault after the select has
-                         * completed successfully. However, because we're not
-                         * updating the timeval, we can't restart the system
-                         * call.
-                         */
-                        if (ret == -ERESTARTNOHAND)
-                                ret = -EINTR;
-                }
-        }
+        ret = core_sys_select(n, inp, outp, exp, &end_time);
+        ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
         if (ret == -ERESTARTNOHAND) {
                 /*
@@ -574,18 +646,24 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
 }
 
 static int do_poll(unsigned int nfds,  struct poll_list *list,
-                   struct poll_wqueues *wait, s64 *timeout)
+                   struct poll_wqueues *wait, struct timespec *end_time)
 {
-        int count = 0;
         poll_table* pt = &wait->pt;
+        ktime_t expire, *to = NULL;
+        int timed_out = 0, count = 0;
+        unsigned long slack = 0;
 
         /* Optimise the no-wait case */
-        if (!(*timeout))
+        if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
                 pt = NULL;
+                timed_out = 1;
+        }
+
+        if (end_time && !timed_out)
+                slack = estimate_accuracy(end_time);
 
         for (;;) {
                 struct poll_list *walk;
-                long __timeout;
 
                 set_current_state(TASK_INTERRUPTIBLE);
                 for (walk = list; walk != NULL; walk = walk->next) {
@@ -617,27 +695,21 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
                         if (signal_pending(current))
                                 count = -EINTR;
                 }
-                if (count || !*timeout)
+                if (count || timed_out)
                         break;
 
-                if (*timeout < 0) {
-                        /* Wait indefinitely */
-                        __timeout = MAX_SCHEDULE_TIMEOUT;
-                } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT-1)) {
-                        /*
-                         * Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in
-                         * a loop
-                         */
-                        __timeout = MAX_SCHEDULE_TIMEOUT - 1;
-                        *timeout -= __timeout;
-                } else {
-                        __timeout = *timeout;
-                        *timeout = 0;
+                /*
+                 * If this is the first loop and we have a timeout
+                 * given, then we convert to ktime_t and set the to
+                 * pointer to the expiry value.
+                 */
+                if (end_time && !to) {
+                        expire = timespec_to_ktime(*end_time);
+                        to = &expire;
                 }
 
-                __timeout = schedule_timeout(__timeout);
-                if (*timeout >= 0)
-                        *timeout += __timeout;
+                if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
+                        timed_out = 1;
         }
         __set_current_state(TASK_RUNNING);
         return count;
@@ -646,7 +718,8 @@ static int do_poll(unsigned int nfds,  struct poll_list *list,
 #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list))  / \
                         sizeof(struct pollfd))
 
-int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
+int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
+                struct timespec *end_time)
 {
         struct poll_wqueues table;
         int err = -EFAULT, fdcount, len, size;
@@ -686,7 +759,7 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
         }
 
         poll_initwait(&table);
-        fdcount = do_poll(nfds, head, &table, timeout);
+        fdcount = do_poll(nfds, head, &table, end_time);
         poll_freewait(&table);
 
         for (walk = head; walk; walk = walk->next) {
@@ -712,16 +785,21 @@ out_fds:
 
 static long do_restart_poll(struct restart_block *restart_block)
 {
-        struct pollfd __user *ufds = (struct pollfd __user*)restart_block->arg0;
-        int nfds = restart_block->arg1;
-        s64 timeout = ((s64)restart_block->arg3<<32) | (s64)restart_block->arg2;
+        struct pollfd __user *ufds = restart_block->poll.ufds;
+        int nfds = restart_block->poll.nfds;
+        struct timespec *to = NULL, end_time;
         int ret;
 
-        ret = do_sys_poll(ufds, nfds, &timeout);
+        if (restart_block->poll.has_timeout) {
+                end_time.tv_sec = restart_block->poll.tv_sec;
+                end_time.tv_nsec = restart_block->poll.tv_nsec;
+                to = &end_time;
+        }
+
+        ret = do_sys_poll(ufds, nfds, to);
+
         if (ret == -EINTR) {
                 restart_block->fn = do_restart_poll;
-                restart_block->arg2 = timeout & 0xFFFFFFFF;
-                restart_block->arg3 = (u64)timeout >> 32;
                 ret = -ERESTART_RESTARTBLOCK;
         }
         return ret;
@@ -730,31 +808,32 @@ static long do_restart_poll(struct restart_block *restart_block)
 asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
                         long timeout_msecs)
 {
-        s64 timeout_jiffies;
+        struct timespec end_time, *to = NULL;
         int ret;
 
-        if (timeout_msecs > 0) {
-#if HZ > 1000
-                /* We can only overflow if HZ > 1000 */
-                if (timeout_msecs / 1000 > (s64)0x7fffffffffffffffULL / (s64)HZ)
-                        timeout_jiffies = -1;
-                else
-#endif
-                        timeout_jiffies = msecs_to_jiffies(timeout_msecs) + 1;
-        } else {
-                /* Infinite (< 0) or no (0) timeout */
-                timeout_jiffies = timeout_msecs;
+        if (timeout_msecs >= 0) {
+                to = &end_time;
+                poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
+                        NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
         }
 
-        ret = do_sys_poll(ufds, nfds, &timeout_jiffies);
+        ret = do_sys_poll(ufds, nfds, to);
+
         if (ret == -EINTR) {
                 struct restart_block *restart_block;
+
                 restart_block = &current_thread_info()->restart_block;
                 restart_block->fn = do_restart_poll;
-                restart_block->arg0 = (unsigned long)ufds;
-                restart_block->arg1 = nfds;
-                restart_block->arg2 = timeout_jiffies & 0xFFFFFFFF;
-                restart_block->arg3 = (u64)timeout_jiffies >> 32;
+                restart_block->poll.ufds = ufds;
+                restart_block->poll.nfds = nfds;
+
+                if (timeout_msecs >= 0) {
+                        restart_block->poll.tv_sec = end_time.tv_sec;
+                        restart_block->poll.tv_nsec = end_time.tv_nsec;
+                        restart_block->poll.has_timeout = 1;
+                } else
+                        restart_block->poll.has_timeout = 0;
+
                 ret = -ERESTART_RESTARTBLOCK;
         }
         return ret;
@@ -766,21 +845,16 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
         size_t sigsetsize)
 {
         sigset_t ksigmask, sigsaved;
-        struct timespec ts;
-        s64 timeout = -1;
+        struct timespec ts, end_time, *to = NULL;
         int ret;
 
         if (tsp) {
                 if (copy_from_user(&ts, tsp, sizeof(ts)))
                         return -EFAULT;
 
-                /* Cast to u64 to make GCC stop complaining */
-                if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS)
-                        timeout = -1;   /* infinite */
-                else {
-                        timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ);
-                        timeout += ts.tv_sec * HZ;
-                }
+                to = &end_time;
+                if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+                        return -EINVAL;
         }
 
         if (sigmask) {
@@ -794,7 +868,7 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
                 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
         }
 
-        ret = do_sys_poll(ufds, nfds, &timeout);
+        ret = do_sys_poll(ufds, nfds, to);
 
         /* We can restart this syscall, usually */
         if (ret == -EINTR) {
@@ -812,31 +886,7 @@ asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
         } else if (sigmask)
                 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. */
-                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
-                         * memory, we don't want the Linux-specific update to
-                         * the timeval to cause a fault after the select has
-                         * completed successfully. However, because we're not
-                         * updating the timeval, we can't restart the system
-                         * call.
-                         */
-                        if (ret == -ERESTARTNOHAND && timeout >= 0)
-                                ret = -EINTR;
-                }
-        }
+        ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
         return ret;
 }