[GIT PULL] core/signal for v2.6.33

Ingo Molnar
2009-12-03T18:47:43Z

Linus,

Please pull the latest core-signal-for-linus git tree from:

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

Thanks,

Ingo

------------------>
Naohiro Ooiwa (1):
signal: Print warning message when dropping signals

Sebastian Andrzej Siewior (1):
signal: Fix alternate signal stack check

Documentation/kernel-parameters.txt | 11 +++++++-
include/linux/sched.h | 13 +++++++--
kernel/signal.c | 46 +++++++++++++++++++++++++----------
3 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9107b38..3bbd92f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2032,8 +2032,15 @@ 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
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 75e6e60..0f67914 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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)
diff --git a/kernel/signal.c b/kernel/signal.c
index 6705320..fe08008 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -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)