perf: Separate find_get_context() from event initialization

Separate find_get_context() from the event allocation and
initialization so that we may make find_get_context() depend
on the event pmu in a later patch.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 8462e69..a3c86a8 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -827,6 +827,8 @@ perf_install_in_context(struct perf_event_context *ctx,
 {
        struct task_struct *task = ctx->task;
 
+       event->ctx = ctx;
+
        if (!task) {
                /*
                 * Per cpu events are installed via an smp call and
@@ -5038,20 +5040,17 @@ struct pmu *perf_init_event(struct perf_event *event)
  * Allocate and initialize a event structure
  */
 static struct perf_event *
-perf_event_alloc(struct perf_event_attr *attr,
-                  int cpu,
-                  struct perf_event_context *ctx,
+perf_event_alloc(struct perf_event_attr *attr, int cpu,
                   struct perf_event *group_leader,
                   struct perf_event *parent_event,
-                  perf_overflow_handler_t overflow_handler,
-                  gfp_t gfpflags)
+                  perf_overflow_handler_t overflow_handler)
 {
        struct pmu *pmu;
        struct perf_event *event;
        struct hw_perf_event *hwc;
        long err;
 
-       event = kzalloc(sizeof(*event), gfpflags);
+       event = kzalloc(sizeof(*event), GFP_KERNEL);
        if (!event)
                return ERR_PTR(-ENOMEM);
 
@@ -5076,7 +5075,6 @@ perf_event_alloc(struct perf_event_attr *attr,
        event->attr             = *attr;
        event->group_leader     = group_leader;
        event->pmu              = NULL;
-       event->ctx              = ctx;
        event->oncpu            = -1;
 
        event->parent           = parent_event;
@@ -5321,20 +5319,26 @@ SYSCALL_DEFINE5(perf_event_open,
        if (event_fd < 0)
                return event_fd;
 
+       event = perf_event_alloc(&attr, cpu, group_leader, NULL, NULL);
+       if (IS_ERR(event)) {
+               err = PTR_ERR(event);
+               goto err_fd;
+       }
+
        /*
         * Get the target context (task or percpu):
         */
        ctx = find_get_context(pid, cpu);
        if (IS_ERR(ctx)) {
                err = PTR_ERR(ctx);
-               goto err_fd;
+               goto err_alloc;
        }
 
        if (group_fd != -1) {
                group_leader = perf_fget_light(group_fd, &fput_needed);
                if (IS_ERR(group_leader)) {
                        err = PTR_ERR(group_leader);
-                       goto err_put_context;
+                       goto err_context;
                }
                group_file = group_leader->filp;
                if (flags & PERF_FLAG_FD_OUTPUT)
@@ -5354,37 +5358,30 @@ SYSCALL_DEFINE5(perf_event_open,
                 * becoming part of another group-sibling):
                 */
                if (group_leader->group_leader != group_leader)
-                       goto err_put_context;
+                       goto err_context;
                /*
                 * Do not allow to attach to a group in a different
                 * task or CPU context:
                 */
                if (group_leader->ctx != ctx)
-                       goto err_put_context;
+                       goto err_context;
                /*
                 * Only a group leader can be exclusive or pinned
                 */
                if (attr.exclusive || attr.pinned)
-                       goto err_put_context;
-       }
-
-       event = perf_event_alloc(&attr, cpu, ctx, group_leader,
-                                    NULL, NULL, GFP_KERNEL);
-       if (IS_ERR(event)) {
-               err = PTR_ERR(event);
-               goto err_put_context;
+                       goto err_context;
        }
 
        if (output_event) {
                err = perf_event_set_output(event, output_event);
                if (err)
-                       goto err_free_put_context;
+                       goto err_context;
        }
 
        event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR);
        if (IS_ERR(event_file)) {
                err = PTR_ERR(event_file);
-               goto err_free_put_context;
+               goto err_context;
        }
 
        event->filp = event_file;
@@ -5410,11 +5407,11 @@ SYSCALL_DEFINE5(perf_event_open,
        fd_install(event_fd, event_file);
        return event_fd;
 
-err_free_put_context:
-       free_event(event);
-err_put_context:
+err_context:
        fput_light(group_file, fput_needed);
        put_ctx(ctx);
+err_alloc:
+       free_event(event);
 err_fd:
        put_unused_fd(event_fd);
        return err;
@@ -5432,25 +5429,24 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
                                 pid_t pid,
                                 perf_overflow_handler_t overflow_handler)
 {
-       struct perf_event *event;
        struct perf_event_context *ctx;
+       struct perf_event *event;
        int err;
 
        /*
         * Get the target context (task or percpu):
         */
 
+       event = perf_event_alloc(attr, cpu, NULL, NULL, overflow_handler);
+       if (IS_ERR(event)) {
+               err = PTR_ERR(event);
+               goto err;
+       }
+
        ctx = find_get_context(pid, cpu);
        if (IS_ERR(ctx)) {
                err = PTR_ERR(ctx);
-               goto err_exit;
-       }
-
-       event = perf_event_alloc(attr, cpu, ctx, NULL,
-                                NULL, overflow_handler, GFP_KERNEL);
-       if (IS_ERR(event)) {
-               err = PTR_ERR(event);
-               goto err_put_context;
+               goto err_free;
        }
 
        event->filp = NULL;
@@ -5468,9 +5464,9 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
 
        return event;
 
- err_put_context:
-       put_ctx(ctx);
- err_exit:
+err_free:
+       free_event(event);
+err:
        return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
@@ -5498,9 +5494,9 @@ inherit_event(struct perf_event *parent_event,
                parent_event = parent_event->parent;
 
        child_event = perf_event_alloc(&parent_event->attr,
-                                          parent_event->cpu, child_ctx,
+                                          parent_event->cpu,
                                           group_leader, parent_event,
-                                          NULL, GFP_KERNEL);
+                                          NULL);
        if (IS_ERR(child_event))
                return child_event;
        get_ctx(child_ctx);
@@ -5525,6 +5521,7 @@ inherit_event(struct perf_event *parent_event,
                local64_set(&hwc->period_left, sample_period);
        }
 
+       child_event->ctx = child_ctx;
        child_event->overflow_handler = parent_event->overflow_handler;
 
        /*