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Subject[RFC][PATCH 11/19] 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>
---
kernel/perf_event.c | 73 ++++++++++++++++++++++++----------------------------
1 file changed, 35 insertions(+), 38 deletions(-)

Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -827,6 +827,8 @@ perf_install_in_context(struct perf_even
{
struct task_struct *task = ctx->task;

+ event->ctx = ctx;
+
if (!task) {
/*
* Per cpu events are installed via an smp call and
@@ -5037,20 +5039,17 @@ struct pmu *perf_init_event(struct perf_
* 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);

@@ -5075,7 +5074,6 @@ perf_event_alloc(struct perf_event_attr
event->attr = *attr;
event->group_leader = group_leader;
event->pmu = NULL;
- event->ctx = ctx;
event->oncpu = -1;

event->parent = parent_event;
@@ -5320,20 +5318,26 @@ 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)
@@ -5353,37 +5357,30 @@ 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;
@@ -5409,11 +5406,11 @@ 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;
@@ -5431,25 +5428,24 @@ perf_event_create_kernel_counter(struct
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;
@@ -5467,9 +5463,9 @@ perf_event_create_kernel_counter(struct

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);
@@ -5497,9 +5493,9 @@ inherit_event(struct perf_event *parent_
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);
@@ -5524,6 +5520,7 @@ inherit_event(struct perf_event *parent_
local64_set(&hwc->period_left, sample_period);
}

+ child_event->ctx = child_ctx;
child_event->overflow_handler = parent_event->overflow_handler;

/*



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