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Date: Tue, 15 Apr 2008 17:23:14 +0530
From: "K. Prasad" <prasad@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, a.p.zijlstra@...llo.nl, mingo@...e.hu,
mathieu.desnoyers@...ymtl.ca
Subject: [RFC PATCH 1/2] Marker probes in futex.c
We place a probe at the function entry for each futex operation,
and also at each point where a futex operation fails.
Signed-off-by: K.Prasad <prasad@...ux.vnet.ibm.com>
---
kernel/futex.c | 110 +++++++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 88 insertions(+), 22 deletions(-)
Index: linux-2.6.25-rc8-mm2/kernel/futex.c
===================================================================
--- linux-2.6.25-rc8-mm2.orig/kernel/futex.c
+++ linux-2.6.25-rc8-mm2/kernel/futex.c
@@ -737,8 +737,14 @@ static int futex_wake(u32 __user *uaddr,
union futex_key key;
int ret;
- if (!bitset)
- return -EINVAL;
+ trace_mark(futex_wake_called, "uaddr:%p fshared:%p nr_wake:%d "
+ "bitset:%d",
+ uaddr, fshared, nr_wake, bitset);
+
+ if (unlikely(!bitset)) {
+ ret = -EINVAL;
+ goto out;
+ }
futex_lock_mm(fshared);
@@ -770,6 +776,8 @@ static int futex_wake(u32 __user *uaddr,
spin_unlock(&hb->lock);
out:
futex_unlock_mm(fshared);
+ if (unlikely(ret != 0))
+ trace_mark(futex_wake_failed, "uaddr:%p ret:%d", uaddr, ret);
return ret;
}
@@ -901,6 +909,14 @@ static int futex_requeue(u32 __user *uad
struct futex_q *this, *next;
int ret, drop_count = 0;
+ /*
+ * Call this probe futex_cmp_requeue_called, although this function is
+ * common to both FUTEX_REQUEUE and FUTEX_CMP_REQUEUE. This is because
+ * FUTEX_REQUEUE is deprecated.
+ */
+ trace_mark(futex_cmp_requeue_called, "uaddr1:%p fshared:%p uaddr2:%p "
+ "nr_wake:%d nr_requeue:%d cmpval:%p",
+ uaddr1, fshared, uaddr2, nr_wake, nr_requeue, cmpval);
retry:
futex_lock_mm(fshared);
@@ -908,8 +924,12 @@ static int futex_requeue(u32 __user *uad
if (unlikely(ret != 0))
goto out;
ret = get_futex_key(uaddr2, fshared, &key2);
- if (unlikely(ret != 0))
+ if (unlikely(ret != 0)) {
+ trace_mark(futex_cmp_requeue_uaddr2_failed, "uaddr1:%p "
+ "uaddr2:%p ret:%d",
+ uaddr1, uaddr2, ret);
goto out;
+ }
hb1 = hash_futex(&key1);
hb2 = hash_futex(&key2);
@@ -984,6 +1004,9 @@ out_unlock:
out:
futex_unlock_mm(fshared);
+ if (unlikely(ret != 0))
+ trace_mark(futex_cmp_requeue_failed, "uaddr1:%p ret:%d", uaddr1,
+ ret);
return ret;
}
@@ -1182,8 +1205,14 @@ static int futex_wait(u32 __user *uaddr,
struct hrtimer_sleeper t;
int rem = 0;
- if (!bitset)
- return -EINVAL;
+ trace_mark(futex_wait_called, "uaddr:%p fshared:%p val:%u "
+ "abs_time:%p bitset:%d",
+ uaddr, fshared, val, abs_time, bitset);
+
+ if (!bitset) {
+ ret = -EINVAL;
+ goto out;
+ }
q.pi_state = NULL;
q.bitset = bitset;
@@ -1231,11 +1260,13 @@ static int futex_wait(u32 __user *uaddr,
if (!ret)
goto retry;
- return ret;
+ goto out;
}
ret = -EWOULDBLOCK;
- if (uval != val)
+ if (uval != val) {
+ trace_mark(futex_wait_uval, "uaddr:%p uval:%u", uval, uaddr);
goto out_unlock_release_sem;
+ }
/* Only actually queue if *uaddr contained val. */
__queue_me(&q, hb);
@@ -1292,6 +1323,7 @@ static int futex_wait(u32 __user *uaddr,
destroy_hrtimer_on_stack(&t.timer);
}
}
+ trace_mark(futex_wait_after_sched, "uaddr:%p", uaddr);
__set_current_state(TASK_RUNNING);
/*
@@ -1302,16 +1334,19 @@ static int futex_wait(u32 __user *uaddr,
/* If we were woken (and unqueued), we succeeded, whatever. */
if (!unqueue_me(&q))
return 0;
- if (rem)
- return -ETIMEDOUT;
+ if (rem) {
+ ret = -ETIMEDOUT;
+ goto out;
+ }
/*
* We expect signal_pending(current), but another thread may
* have handled it for us already.
*/
- if (!abs_time)
- return -ERESTARTSYS;
- else {
+ if (!abs_time) {
+ ret = -ERESTARTSYS;
+ goto out;
+ } else {
struct restart_block *restart;
restart = ¤t_thread_info()->restart_block;
restart->fn = futex_wait_restart;
@@ -1323,7 +1358,8 @@ static int futex_wait(u32 __user *uaddr,
if (fshared)
restart->futex.flags |= FLAGS_SHARED;
- return -ERESTART_RESTARTBLOCK;
+ ret = -ERESTART_RESTARTBLOCK;
+ goto out;
}
out_unlock_release_sem:
@@ -1331,6 +1367,10 @@ static int futex_wait(u32 __user *uaddr,
out_release_sem:
futex_unlock_mm(fshared);
+
+ out:
+ if (unlikely(ret != 0))
+ trace_mark(futex_wait_failed, "uaddr:%p ret:%d", uaddr, ret);
return ret;
}
@@ -1366,8 +1406,14 @@ static int futex_lock_pi(u32 __user *uad
struct futex_q q;
int ret, lock_taken, ownerdied = 0, attempt = 0;
- if (refill_pi_state_cache())
- return -ENOMEM;
+ trace_mark(futex_lock_pi_called, "uaddr:%p fshared:%p detect:%d "
+ "time:%p trylock:%d",
+ uaddr, fshared, detect, time, trylock);
+
+ if (refill_pi_state_cache()) {
+ ret = -ENOMEM;
+ goto out;
+ }
if (time) {
to = &timeout;
@@ -1588,7 +1634,9 @@ static int futex_lock_pi(u32 __user *uad
if (to)
destroy_hrtimer_on_stack(&to->timer);
- return ret != -EINTR ? ret : -ERESTARTNOINTR;
+ if (ret == -EINTR)
+ ret = -ERESTARTNOINTR;
+ goto out;
out_unlock_release_sem:
queue_unlock(&q, hb);
@@ -1597,7 +1645,7 @@ static int futex_lock_pi(u32 __user *uad
futex_unlock_mm(fshared);
if (to)
destroy_hrtimer_on_stack(&to->timer);
- return ret;
+ goto out;
uaddr_faulted:
/*
@@ -1624,6 +1672,9 @@ static int futex_lock_pi(u32 __user *uad
if (!ret && (uval != -EFAULT))
goto retry;
+ out:
+ if (unlikely(ret != 0))
+ trace_mark(futex_lock_pi_failed, "uaddr:%p ret:%d", uaddr, ret);
if (to)
destroy_hrtimer_on_stack(&to->timer);
return ret;
@@ -1643,14 +1694,20 @@ static int futex_unlock_pi(u32 __user *u
union futex_key key;
int ret, attempt = 0;
+ trace_mark(futex_unlock_pi_called, "uaddr:%p fshared:%p",
+ uaddr, fshared);
retry:
- if (get_user(uval, uaddr))
- return -EFAULT;
+ if (get_user(uval, uaddr)) {
+ ret = -EFAULT;
+ goto out_return;
+ }
/*
* We release only a lock we actually own:
*/
- if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
- return -EPERM;
+ if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current)) {
+ ret = -EPERM;
+ goto out_return;
+ }
/*
* First take all the futex related locks:
*/
@@ -1715,7 +1772,7 @@ out_unlock:
out:
futex_unlock_mm(fshared);
- return ret;
+ goto out_return;
pi_faulted:
/*
@@ -1743,6 +1800,10 @@ pi_faulted:
if (!ret && (uval != -EFAULT))
goto retry;
+out_return:
+ if (unlikely(ret != 0))
+ trace_mark(futex_unlock_pi_failed, "uaddr:%p ret:%d",
+ uaddr, ret);
return ret;
}
@@ -2120,6 +2181,11 @@ long do_futex(u32 __user *uaddr, int op,
default:
ret = -ENOSYS;
}
+ trace_mark(do_futex_probe, "uaddr: %lu op:%d val:%lu timeout:%p "
+ "uaddr2:%lu val2:%lu val3:%lu ret:%d",
+ (unsigned long)uaddr, op, (unsigned long)val,
+ timeout, (unsigned long)uaddr2, (unsigned long)val2,
+ (unsigned long)val3, ret);
return ret;
}
--
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