perf_counter: Propagate inheritance failures down the fork() path

Fail fork() when we fail inheritance for some reason (-ENOMEM most likely).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090525124600.324656474@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 19 insertions, 11 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index b1f2bac09f9..d3e85de9bf1 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -566,7 +566,7 @@ extern void perf_counter_task_sched_in(struct task_struct *task, int cpu);
 extern void perf_counter_task_sched_out(struct task_struct *task,
                                         struct task_struct *next, int cpu);
 extern void perf_counter_task_tick(struct task_struct *task, int cpu);
-extern void perf_counter_init_task(struct task_struct *child);
+extern int perf_counter_init_task(struct task_struct *child);
 extern void perf_counter_exit_task(struct task_struct *child);
 extern void perf_counter_do_pending(void);
 extern void perf_counter_print_debug(void);
@@ -631,7 +631,7 @@ perf_counter_task_sched_out(struct task_struct *task,
                             struct task_struct *next, int cpu)          { }
 static inline void
 perf_counter_task_tick(struct task_struct *task, int cpu)               { }
-static inline void perf_counter_init_task(struct task_struct *child)    { }
+static inline int perf_counter_init_task(struct task_struct *child)     { }
 static inline void perf_counter_exit_task(struct task_struct *child)    { }
 static inline void perf_counter_do_pending(void)                        { }
 static inline void perf_counter_print_debug(void)                       { }
diff --git a/kernel/fork.c b/kernel/fork.c
index 675e01e9072..c07c3335cea 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1095,7 +1095,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
         /* Perform scheduler related setup. Assign this task to a CPU. */
         sched_fork(p, clone_flags);
-        perf_counter_init_task(p);
+
+        retval = perf_counter_init_task(p);
+        if (retval)
+                goto bad_fork_cleanup_policy;
 
         if ((retval = audit_alloc(p)))
                 goto bad_fork_cleanup_policy;
@@ -1295,6 +1298,7 @@ bad_fork_cleanup_semundo:
 bad_fork_cleanup_audit:
         audit_free(p);
 bad_fork_cleanup_policy:
+        perf_counter_exit_task(p);
 #ifdef CONFIG_NUMA
         mpol_put(p->mempolicy);
 bad_fork_cleanup_cgroup:
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 217dbcce2eb..7a7a144870e 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -3434,18 +3434,23 @@ again:
 /*
  * Initialize the perf_counter context in task_struct
  */
-void perf_counter_init_task(struct task_struct *child)
+int perf_counter_init_task(struct task_struct *child)
 {
         struct perf_counter_context *child_ctx, *parent_ctx;
         struct perf_counter *counter;
         struct task_struct *parent = current;
         int inherited_all = 1;
+        int ret = 0;
 
         child->perf_counter_ctxp = NULL;
 
         mutex_init(&child->perf_counter_mutex);
         INIT_LIST_HEAD(&child->perf_counter_list);
 
+        parent_ctx = parent->perf_counter_ctxp;
+        if (likely(!parent_ctx || !parent_ctx->nr_counters))
+                return 0;
+
         /*
          * This is executed from the parent task context, so inherit
          * counters that have been marked for cloning.
@@ -3454,11 +3459,7 @@ void perf_counter_init_task(struct task_struct *child)
 
         child_ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL);
         if (!child_ctx)
-                return;
-
-        parent_ctx = parent->perf_counter_ctxp;
-        if (likely(!parent_ctx || !parent_ctx->nr_counters))
-                return;
+                return -ENOMEM;
 
         __perf_counter_init_context(child_ctx, child);
         child->perf_counter_ctxp = child_ctx;
@@ -3482,8 +3483,9 @@ void perf_counter_init_task(struct task_struct *child)
                         continue;
                 }
 
-                if (inherit_group(counter, parent,
-                                  parent_ctx, child, child_ctx)) {
+                ret = inherit_group(counter, parent, parent_ctx,
+                                             child, child_ctx);
+                if (ret) {
                         inherited_all = 0;
                         break;
                 }
@@ -3505,6 +3507,8 @@ void perf_counter_init_task(struct task_struct *child)
         }
 
         mutex_unlock(&parent_ctx->mutex);
+
+        return ret;
 }
 
 static void __cpuinit perf_counter_init_cpu(int cpu)