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-rw-r--r--kernel/sys.c514
1 files changed, 352 insertions, 162 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index f91218a5463..7ef7f6054c2 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -95,99 +95,304 @@ int cad_pid = 1;
* and the like.
*/
-static struct notifier_block *reboot_notifier_list;
-static DEFINE_RWLOCK(notifier_lock);
+static BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
+
+/*
+ * Notifier chain core routines. The exported routines below
+ * are layered on top of these, with appropriate locking added.
+ */
+
+static int notifier_chain_register(struct notifier_block **nl,
+ struct notifier_block *n)
+{
+ while ((*nl) != NULL) {
+ if (n->priority > (*nl)->priority)
+ break;
+ nl = &((*nl)->next);
+ }
+ n->next = *nl;
+ rcu_assign_pointer(*nl, n);
+ return 0;
+}
+
+static int notifier_chain_unregister(struct notifier_block **nl,
+ struct notifier_block *n)
+{
+ while ((*nl) != NULL) {
+ if ((*nl) == n) {
+ rcu_assign_pointer(*nl, n->next);
+ return 0;
+ }
+ nl = &((*nl)->next);
+ }
+ return -ENOENT;
+}
+
+static int __kprobes notifier_call_chain(struct notifier_block **nl,
+ unsigned long val, void *v)
+{
+ int ret = NOTIFY_DONE;
+ struct notifier_block *nb;
+
+ nb = rcu_dereference(*nl);
+ while (nb) {
+ ret = nb->notifier_call(nb, val, v);
+ if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
+ break;
+ nb = rcu_dereference(nb->next);
+ }
+ return ret;
+}
+
+/*
+ * Atomic notifier chain routines. Registration and unregistration
+ * use a mutex, and call_chain is synchronized by RCU (no locks).
+ */
/**
- * notifier_chain_register - Add notifier to a notifier chain
- * @list: Pointer to root list pointer
+ * atomic_notifier_chain_register - Add notifier to an atomic notifier chain
+ * @nh: Pointer to head of the atomic notifier chain
* @n: New entry in notifier chain
*
- * Adds a notifier to a notifier chain.
+ * Adds a notifier to an atomic notifier chain.
*
* Currently always returns zero.
*/
+
+int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
+ struct notifier_block *n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_register(&nh->head, n);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
+
+/**
+ * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
+ * @nh: Pointer to head of the atomic notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from an atomic notifier chain.
+ *
+ * Returns zero on success or %-ENOENT on failure.
+ */
+int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
+ struct notifier_block *n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&nh->lock, flags);
+ ret = notifier_chain_unregister(&nh->head, n);
+ spin_unlock_irqrestore(&nh->lock, flags);
+ synchronize_rcu();
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
+
+/**
+ * atomic_notifier_call_chain - Call functions in an atomic notifier chain
+ * @nh: Pointer to head of the atomic notifier chain
+ * @val: Value passed unmodified to notifier function
+ * @v: Pointer passed unmodified to notifier function
+ *
+ * Calls each function in a notifier chain in turn. The functions
+ * run in an atomic context, so they must not block.
+ * This routine uses RCU to synchronize with changes to the chain.
+ *
+ * If the return value of the notifier can be and'ed
+ * with %NOTIFY_STOP_MASK then atomic_notifier_call_chain
+ * will return immediately, with the return value of
+ * the notifier function which halted execution.
+ * Otherwise the return value is the return value
+ * of the last notifier function called.
+ */
-int notifier_chain_register(struct notifier_block **list, struct notifier_block *n)
+int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
+ unsigned long val, void *v)
{
- write_lock(&notifier_lock);
- while(*list)
- {
- if(n->priority > (*list)->priority)
- break;
- list= &((*list)->next);
- }
- n->next = *list;
- *list=n;
- write_unlock(&notifier_lock);
- return 0;
+ int ret;
+
+ rcu_read_lock();
+ ret = notifier_call_chain(&nh->head, val, v);
+ rcu_read_unlock();
+ return ret;
}
-EXPORT_SYMBOL(notifier_chain_register);
+EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
+
+/*
+ * Blocking notifier chain routines. All access to the chain is
+ * synchronized by an rwsem.
+ */
/**
- * notifier_chain_unregister - Remove notifier from a notifier chain
- * @nl: Pointer to root list pointer
+ * blocking_notifier_chain_register - Add notifier to a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
* @n: New entry in notifier chain
*
- * Removes a notifier from a notifier chain.
+ * Adds a notifier to a blocking notifier chain.
+ * Must be called in process context.
*
- * Returns zero on success, or %-ENOENT on failure.
+ * Currently always returns zero.
*/
-int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n)
+int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+ struct notifier_block *n)
{
- write_lock(&notifier_lock);
- while((*nl)!=NULL)
- {
- if((*nl)==n)
- {
- *nl=n->next;
- write_unlock(&notifier_lock);
- return 0;
- }
- nl=&((*nl)->next);
- }
- write_unlock(&notifier_lock);
- return -ENOENT;
+ int ret;
+
+ /*
+ * This code gets used during boot-up, when task switching is
+ * not yet working and interrupts must remain disabled. At
+ * such times we must not call down_write().
+ */
+ if (unlikely(system_state == SYSTEM_BOOTING))
+ return notifier_chain_register(&nh->head, n);
+
+ down_write(&nh->rwsem);
+ ret = notifier_chain_register(&nh->head, n);
+ up_write(&nh->rwsem);
+ return ret;
}
-EXPORT_SYMBOL(notifier_chain_unregister);
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
/**
- * notifier_call_chain - Call functions in a notifier chain
- * @n: Pointer to root pointer of notifier chain
+ * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from a blocking notifier chain.
+ * Must be called from process context.
+ *
+ * Returns zero on success or %-ENOENT on failure.
+ */
+int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
+ struct notifier_block *n)
+{
+ int ret;
+
+ /*
+ * This code gets used during boot-up, when task switching is
+ * not yet working and interrupts must remain disabled. At
+ * such times we must not call down_write().
+ */
+ if (unlikely(system_state == SYSTEM_BOOTING))
+ return notifier_chain_unregister(&nh->head, n);
+
+ down_write(&nh->rwsem);
+ ret = notifier_chain_unregister(&nh->head, n);
+ up_write(&nh->rwsem);
+ return ret;
+}
+
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
+
+/**
+ * blocking_notifier_call_chain - Call functions in a blocking notifier chain
+ * @nh: Pointer to head of the blocking notifier chain
* @val: Value passed unmodified to notifier function
* @v: Pointer passed unmodified to notifier function
*
- * Calls each function in a notifier chain in turn.
+ * Calls each function in a notifier chain in turn. The functions
+ * run in a process context, so they are allowed to block.
*
- * If the return value of the notifier can be and'd
- * with %NOTIFY_STOP_MASK, then notifier_call_chain
+ * If the return value of the notifier can be and'ed
+ * with %NOTIFY_STOP_MASK then blocking_notifier_call_chain
* will return immediately, with the return value of
* the notifier function which halted execution.
- * Otherwise, the return value is the return value
+ * Otherwise the return value is the return value
* of the last notifier function called.
*/
-int __kprobes notifier_call_chain(struct notifier_block **n, unsigned long val, void *v)
+int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
+ unsigned long val, void *v)
{
- int ret=NOTIFY_DONE;
- struct notifier_block *nb = *n;
+ int ret;
- while(nb)
- {
- ret=nb->notifier_call(nb,val,v);
- if(ret&NOTIFY_STOP_MASK)
- {
- return ret;
- }
- nb=nb->next;
- }
+ down_read(&nh->rwsem);
+ ret = notifier_call_chain(&nh->head, val, v);
+ up_read(&nh->rwsem);
return ret;
}
-EXPORT_SYMBOL(notifier_call_chain);
+EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
+
+/*
+ * Raw notifier chain routines. There is no protection;
+ * the caller must provide it. Use at your own risk!
+ */
+
+/**
+ * raw_notifier_chain_register - Add notifier to a raw notifier chain
+ * @nh: Pointer to head of the raw notifier chain
+ * @n: New entry in notifier chain
+ *
+ * Adds a notifier to a raw notifier chain.
+ * All locking must be provided by the caller.
+ *
+ * Currently always returns zero.
+ */
+
+int raw_notifier_chain_register(struct raw_notifier_head *nh,
+ struct notifier_block *n)
+{
+ return notifier_chain_register(&nh->head, n);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
+
+/**
+ * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
+ * @nh: Pointer to head of the raw notifier chain
+ * @n: Entry to remove from notifier chain
+ *
+ * Removes a notifier from a raw notifier chain.
+ * All locking must be provided by the caller.
+ *
+ * Returns zero on success or %-ENOENT on failure.
+ */
+int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
+ struct notifier_block *n)
+{
+ return notifier_chain_unregister(&nh->head, n);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
+
+/**
+ * raw_notifier_call_chain - Call functions in a raw notifier chain
+ * @nh: Pointer to head of the raw notifier chain
+ * @val: Value passed unmodified to notifier function
+ * @v: Pointer passed unmodified to notifier function
+ *
+ * Calls each function in a notifier chain in turn. The functions
+ * run in an undefined context.
+ * All locking must be provided by the caller.
+ *
+ * If the return value of the notifier can be and'ed
+ * with %NOTIFY_STOP_MASK then raw_notifier_call_chain
+ * will return immediately, with the return value of
+ * the notifier function which halted execution.
+ * Otherwise the return value is the return value
+ * of the last notifier function called.
+ */
+
+int raw_notifier_call_chain(struct raw_notifier_head *nh,
+ unsigned long val, void *v)
+{
+ return notifier_call_chain(&nh->head, val, v);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
/**
* register_reboot_notifier - Register function to be called at reboot time
@@ -196,13 +401,13 @@ EXPORT_SYMBOL(notifier_call_chain);
* Registers a function with the list of functions
* to be called at reboot time.
*
- * Currently always returns zero, as notifier_chain_register
+ * Currently always returns zero, as blocking_notifier_chain_register
* always returns zero.
*/
int register_reboot_notifier(struct notifier_block * nb)
{
- return notifier_chain_register(&reboot_notifier_list, nb);
+ return blocking_notifier_chain_register(&reboot_notifier_list, nb);
}
EXPORT_SYMBOL(register_reboot_notifier);
@@ -219,23 +424,11 @@ EXPORT_SYMBOL(register_reboot_notifier);
int unregister_reboot_notifier(struct notifier_block * nb)
{
- return notifier_chain_unregister(&reboot_notifier_list, nb);
+ return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
}
EXPORT_SYMBOL(unregister_reboot_notifier);
-#ifndef CONFIG_SECURITY
-int capable(int cap)
-{
- if (cap_raised(current->cap_effective, cap)) {
- current->flags |= PF_SUPERPRIV;
- return 1;
- }
- return 0;
-}
-EXPORT_SYMBOL(capable);
-#endif
-
static int set_one_prio(struct task_struct *p, int niceval, int error)
{
int no_nice;
@@ -392,7 +585,7 @@ EXPORT_SYMBOL_GPL(emergency_restart);
void kernel_restart_prepare(char *cmd)
{
- notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
+ blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
system_state = SYSTEM_RESTART;
device_shutdown();
}
@@ -442,7 +635,7 @@ EXPORT_SYMBOL_GPL(kernel_kexec);
void kernel_shutdown_prepare(enum system_states state)
{
- notifier_call_chain(&reboot_notifier_list,
+ blocking_notifier_call_chain(&reboot_notifier_list,
(state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
system_state = state;
device_shutdown();
@@ -1009,69 +1202,24 @@ asmlinkage long sys_times(struct tms __user * tbuf)
*/
if (tbuf) {
struct tms tmp;
+ struct task_struct *tsk = current;
+ struct task_struct *t;
cputime_t utime, stime, cutime, cstime;
-#ifdef CONFIG_SMP
- if (thread_group_empty(current)) {
- /*
- * Single thread case without the use of any locks.
- *
- * We may race with release_task if two threads are
- * executing. However, release task first adds up the
- * counters (__exit_signal) before removing the task
- * from the process tasklist (__unhash_process).
- * __exit_signal also acquires and releases the
- * siglock which results in the proper memory ordering
- * so that the list modifications are always visible
- * after the counters have been updated.
- *
- * If the counters have been updated by the second thread
- * but the thread has not yet been removed from the list
- * then the other branch will be executing which will
- * block on tasklist_lock until the exit handling of the
- * other task is finished.
- *
- * This also implies that the sighand->siglock cannot
- * be held by another processor. So we can also
- * skip acquiring that lock.
- */
- utime = cputime_add(current->signal->utime, current->utime);
- stime = cputime_add(current->signal->utime, current->stime);
- cutime = current->signal->cutime;
- cstime = current->signal->cstime;
- } else
-#endif
- {
+ spin_lock_irq(&tsk->sighand->siglock);
+ utime = tsk->signal->utime;
+ stime = tsk->signal->stime;
+ t = tsk;
+ do {
+ utime = cputime_add(utime, t->utime);
+ stime = cputime_add(stime, t->stime);
+ t = next_thread(t);
+ } while (t != tsk);
- /* Process with multiple threads */
- struct task_struct *tsk = current;
- struct task_struct *t;
-
- read_lock(&tasklist_lock);
- utime = tsk->signal->utime;
- stime = tsk->signal->stime;
- t = tsk;
- do {
- utime = cputime_add(utime, t->utime);
- stime = cputime_add(stime, t->stime);
- t = next_thread(t);
- } while (t != tsk);
+ cutime = tsk->signal->cutime;
+ cstime = tsk->signal->cstime;
+ spin_unlock_irq(&tsk->sighand->siglock);
- /*
- * While we have tasklist_lock read-locked, no dying thread
- * can be updating current->signal->[us]time. Instead,
- * we got their counts included in the live thread loop.
- * However, another thread can come in right now and
- * do a wait call that updates current->signal->c[us]time.
- * To make sure we always see that pair updated atomically,
- * we take the siglock around fetching them.
- */
- spin_lock_irq(&tsk->sighand->siglock);
- cutime = tsk->signal->cutime;
- cstime = tsk->signal->cstime;
- spin_unlock_irq(&tsk->sighand->siglock);
- read_unlock(&tasklist_lock);
- }
tmp.tms_utime = cputime_to_clock_t(utime);
tmp.tms_stime = cputime_to_clock_t(stime);
tmp.tms_cutime = cputime_to_clock_t(cutime);
@@ -1227,7 +1375,7 @@ asmlinkage long sys_setsid(void)
struct pid *pid;
int err = -EPERM;
- down(&tty_sem);
+ mutex_lock(&tty_mutex);
write_lock_irq(&tasklist_lock);
pid = find_pid(PIDTYPE_PGID, group_leader->pid);
@@ -1241,7 +1389,7 @@ asmlinkage long sys_setsid(void)
err = process_group(group_leader);
out:
write_unlock_irq(&tasklist_lock);
- up(&tty_sem);
+ mutex_unlock(&tty_mutex);
return err;
}
@@ -1375,7 +1523,7 @@ static void groups_sort(struct group_info *group_info)
/* a simple bsearch */
int groups_search(struct group_info *group_info, gid_t grp)
{
- int left, right;
+ unsigned int left, right;
if (!group_info)
return 0;
@@ -1383,7 +1531,7 @@ int groups_search(struct group_info *group_info, gid_t grp)
left = 0;
right = group_info->ngroups;
while (left < right) {
- int mid = (left+right)/2;
+ unsigned int mid = (left+right)/2;
int cmp = grp - GROUP_AT(group_info, mid);
if (cmp > 0)
left = mid + 1;
@@ -1433,7 +1581,6 @@ asmlinkage long sys_getgroups(int gidsetsize, gid_t __user *grouplist)
return -EINVAL;
/* no need to grab task_lock here; it cannot change */
- get_group_info(current->group_info);
i = current->group_info->ngroups;
if (gidsetsize) {
if (i > gidsetsize) {
@@ -1446,7 +1593,6 @@ asmlinkage long sys_getgroups(int gidsetsize, gid_t __user *grouplist)
}
}
out:
- put_group_info(current->group_info);
return i;
}
@@ -1487,9 +1633,7 @@ int in_group_p(gid_t grp)
{
int retval = 1;
if (grp != current->fsgid) {
- get_group_info(current->group_info);
retval = groups_search(current->group_info, grp);
- put_group_info(current->group_info);
}
return retval;
}
@@ -1500,9 +1644,7 @@ int in_egroup_p(gid_t grp)
{
int retval = 1;
if (grp != current->egid) {
- get_group_info(current->group_info);
retval = groups_search(current->group_info, grp);
- put_group_info(current->group_info);
}
return retval;
}
@@ -1630,20 +1772,21 @@ asmlinkage long sys_old_getrlimit(unsigned int resource, struct rlimit __user *r
asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit __user *rlim)
{
struct rlimit new_rlim, *old_rlim;
+ unsigned long it_prof_secs;
int retval;
if (resource >= RLIM_NLIMITS)
return -EINVAL;
- if(copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
+ if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
return -EFAULT;
- if (new_rlim.rlim_cur > new_rlim.rlim_max)
- return -EINVAL;
+ if (new_rlim.rlim_cur > new_rlim.rlim_max)
+ return -EINVAL;
old_rlim = current->signal->rlim + resource;
if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
!capable(CAP_SYS_RESOURCE))
return -EPERM;
if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > NR_OPEN)
- return -EPERM;
+ return -EPERM;
retval = security_task_setrlimit(resource, &new_rlim);
if (retval)
@@ -1653,19 +1796,40 @@ asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit __user *rlim)
*old_rlim = new_rlim;
task_unlock(current->group_leader);
- if (resource == RLIMIT_CPU && new_rlim.rlim_cur != RLIM_INFINITY &&
- (cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
- new_rlim.rlim_cur <= cputime_to_secs(
- current->signal->it_prof_expires))) {
- cputime_t cputime = secs_to_cputime(new_rlim.rlim_cur);
+ if (resource != RLIMIT_CPU)
+ goto out;
+
+ /*
+ * RLIMIT_CPU handling. Note that the kernel fails to return an error
+ * code if it rejected the user's attempt to set RLIMIT_CPU. This is a
+ * very long-standing error, and fixing it now risks breakage of
+ * applications, so we live with it
+ */
+ if (new_rlim.rlim_cur == RLIM_INFINITY)
+ goto out;
+
+ it_prof_secs = cputime_to_secs(current->signal->it_prof_expires);
+ if (it_prof_secs == 0 || new_rlim.rlim_cur <= it_prof_secs) {
+ unsigned long rlim_cur = new_rlim.rlim_cur;
+ cputime_t cputime;
+
+ if (rlim_cur == 0) {
+ /*
+ * The caller is asking for an immediate RLIMIT_CPU
+ * expiry. But we use the zero value to mean "it was
+ * never set". So let's cheat and make it one second
+ * instead
+ */
+ rlim_cur = 1;
+ }
+ cputime = secs_to_cputime(rlim_cur);
read_lock(&tasklist_lock);
spin_lock_irq(&current->sighand->siglock);
- set_process_cpu_timer(current, CPUCLOCK_PROF,
- &cputime, NULL);
+ set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
spin_unlock_irq(&current->sighand->siglock);
read_unlock(&tasklist_lock);
}
-
+out:
return 0;
}
@@ -1677,9 +1841,6 @@ asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit __user *rlim)
* a lot simpler! (Which we're not doing right now because we're not
* measuring them yet).
*
- * This expects to be called with tasklist_lock read-locked or better,
- * and the siglock not locked. It may momentarily take the siglock.
- *
* When sampling multiple threads for RUSAGE_SELF, under SMP we might have
* races with threads incrementing their own counters. But since word
* reads are atomic, we either get new values or old values and we don't
@@ -1687,6 +1848,25 @@ asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit __user *rlim)
* the c* fields from p->signal from races with exit.c updating those
* fields when reaping, so a sample either gets all the additions of a
* given child after it's reaped, or none so this sample is before reaping.
+ *
+ * tasklist_lock locking optimisation:
+ * If we are current and single threaded, we do not need to take the tasklist
+ * lock or the siglock. No one else can take our signal_struct away,
+ * no one else can reap the children to update signal->c* counters, and
+ * no one else can race with the signal-> fields.
+ * If we do not take the tasklist_lock, the signal-> fields could be read
+ * out of order while another thread was just exiting. So we place a
+ * read memory barrier when we avoid the lock. On the writer side,
+ * write memory barrier is implied in __exit_signal as __exit_signal releases
+ * the siglock spinlock after updating the signal-> fields.
+ *
+ * We don't really need the siglock when we access the non c* fields
+ * of the signal_struct (for RUSAGE_SELF) even in multithreaded
+ * case, since we take the tasklist lock for read and the non c* signal->
+ * fields are updated only in __exit_signal, which is called with
+ * tasklist_lock taken for write, hence these two threads cannot execute
+ * concurrently.
+ *
*/
static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
@@ -1694,13 +1874,23 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
struct task_struct *t;
unsigned long flags;
cputime_t utime, stime;
+ int need_lock = 0;
memset((char *) r, 0, sizeof *r);
+ utime = stime = cputime_zero;
- if (unlikely(!p->signal))
- return;
+ if (p != current || !thread_group_empty(p))
+ need_lock = 1;
- utime = stime = cputime_zero;
+ if (need_lock) {
+ read_lock(&tasklist_lock);
+ if (unlikely(!p->signal)) {
+ read_unlock(&tasklist_lock);
+ return;
+ }
+ } else
+ /* See locking comments above */
+ smp_rmb();
switch (who) {
case RUSAGE_BOTH:
@@ -1740,6 +1930,8 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
BUG();
}
+ if (need_lock)
+ read_unlock(&tasklist_lock);
cputime_to_timeval(utime, &r->ru_utime);
cputime_to_timeval(stime, &r->ru_stime);
}
@@ -1747,9 +1939,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
{
struct rusage r;
- read_lock(&tasklist_lock);
k_getrusage(p, who, &r);
- read_unlock(&tasklist_lock);
return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-03 23:51:54 +0000