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Merge branch 'core-signal-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'core-signal-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  signal: Print warning message when dropping signals
  signal: Fix alternate signal stack check
This commit is contained in:
Linus Torvalds 2009-12-05 09:52:33 -08:00
commit 69f061e0c2
3 changed files with 52 additions and 18 deletions
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11
Documentation/kernel-parameters.txt
View File

@ -2031,8 +2031,15 @@ and is between 256 and 4096 characters. It is defined in the file
print-fatal-signals=
[KNL] debug: print fatal signals
print-fatal-signals=1: print segfault info to
the kernel console.
If enabled, warn about various signal handling
related application anomalies: too many signals,
too many POSIX.1 timers, fatal signals causing a
coredump - etc.
If you hit the warning due to signal overflow,
you might want to try "ulimit -i unlimited".
default: off.
printk.time= Show timing data prefixed to each printk message line

13
include/linux/sched.h
View File

@ -2086,11 +2086,18 @@ static inline int is_si_special(const struct siginfo *info)
return info <= SEND_SIG_FORCED;
}
/* True if we are on the alternate signal stack. */
/*
* True if we are on the alternate signal stack.
*/
static inline int on_sig_stack(unsigned long sp)
{
return (sp - current->sas_ss_sp < current->sas_ss_size);
#ifdef CONFIG_STACK_GROWSUP
return sp >= current->sas_ss_sp &&
sp - current->sas_ss_sp < current->sas_ss_size;
#else
return sp > current->sas_ss_sp &&
sp - current->sas_ss_sp <= current->sas_ss_size;
#endif
}
static inline int sas_ss_flags(unsigned long sp)

46
kernel/signal.c
View File

@ -22,6 +22,7 @@
#include <linux/ptrace.h>
#include <linux/signal.h>
#include <linux/signalfd.h>
#include <linux/ratelimit.h>
#include <linux/tracehook.h>
#include <linux/capability.h>
#include <linux/freezer.h>
@ -41,6 +42,8 @@
static struct kmem_cache *sigqueue_cachep;
int print_fatal_signals __read_mostly;
static void __user *sig_handler(struct task_struct *t, int sig)
{
return t->sighand->action[sig - 1].sa.sa_handler;
@ -159,7 +162,7 @@ int next_signal(struct sigpending *pending, sigset_t *mask)
{
unsigned long i, *s, *m, x;
int sig = 0;
s = pending->signal.sig;
m = mask->sig;
switch (_NSIG_WORDS) {
@ -184,17 +187,31 @@ int next_signal(struct sigpending *pending, sigset_t *mask)
sig = ffz(~x) + 1;
break;
}
return sig;
}
static inline void print_dropped_signal(int sig)
{
static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
if (!print_fatal_signals)
return;
if (!__ratelimit(&ratelimit_state))
return;
printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
current->comm, current->pid, sig);
}
/*
* allocate a new signal queue record
* - this may be called without locks if and only if t == current, otherwise an
* appopriate lock must be held to stop the target task from exiting
*/
static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
int override_rlimit)
static struct sigqueue *
__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
{
struct sigqueue *q = NULL;
struct user_struct *user;
@ -207,10 +224,15 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
*/
user = get_uid(__task_cred(t)->user);
atomic_inc(&user->sigpending);
if (override_rlimit ||
atomic_read(&user->sigpending) <=
t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur) {
q = kmem_cache_alloc(sigqueue_cachep, flags);
} else {
print_dropped_signal(sig);
}
if (unlikely(q == NULL)) {
atomic_dec(&user->sigpending);
free_uid(user);
@ -869,7 +891,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
else
override_rlimit = 0;
q = __sigqueue_alloc(t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
override_rlimit);
if (q) {
list_add_tail(&q->list, &pending->list);
@ -925,8 +947,6 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
return __send_signal(sig, info, t, group, from_ancestor_ns);
}
int print_fatal_signals;
static void print_fatal_signal(struct pt_regs *regs, int signr)
{
printk("%s/%d: potentially unexpected fatal signal %d.\n",
@ -1293,19 +1313,19 @@ EXPORT_SYMBOL(kill_pid);
* These functions support sending signals using preallocated sigqueue
* structures. This is needed "because realtime applications cannot
* afford to lose notifications of asynchronous events, like timer
* expirations or I/O completions". In the case of Posix Timers
* expirations or I/O completions". In the case of Posix Timers
* we allocate the sigqueue structure from the timer_create. If this
* allocation fails we are able to report the failure to the application
* with an EAGAIN error.
*/
struct sigqueue *sigqueue_alloc(void)
{
struct sigqueue *q;
struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
if (q)
q->flags |= SIGQUEUE_PREALLOC;
return(q);
return q;
}
void sigqueue_free(struct sigqueue *q)