perf: Clean up pmu specific data

The pmu specific data is saved in task_struct now. Remove it from event
context structure.

Remove swap_task_ctx() as well.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250314172700.438923-7-kan.liang@linux.intel.com

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 58f40c89d728ee2441c035d243f6b41f3edebc35..5b8e3aabac02c35bb336ec471e2f93e2ba9cfd1d 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -501,16 +501,6 @@ struct pmu {
         */
        struct kmem_cache               *task_ctx_cache;
 
-       /*
-        * PMU specific parts of task perf event context (i.e. ctx->task_ctx_data)
-        * can be synchronized using this function. See Intel LBR callstack support
-        * implementation and Perf core context switch handling callbacks for usage
-        * examples.
-        */
-       void (*swap_task_ctx)           (struct perf_event_pmu_context *prev_epc,
-                                        struct perf_event_pmu_context *next_epc);
-                                       /* optional */
-
        /*
         * Set up pmu-private data structures for an AUX area
         */
@@ -933,7 +923,6 @@ struct perf_event_pmu_context {
        atomic_t                        refcount; /* event <-> epc */
        struct rcu_head                 rcu_head;
 
-       void                            *task_ctx_data; /* pmu specific data */
        /*
         * Set when one or more (plausibly active) event can't be scheduled
         * due to pmu overcommit or pmu constraints, except tolerant to
@@ -981,7 +970,6 @@ struct perf_event_context {
        int                             nr_user;
        int                             is_active;
 
-       int                             nr_task_data;
        int                             nr_stat;
        int                             nr_freq;
        int                             rotate_disable;

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 992829264577395820dc26c603c5f260f3e7d20b..4ce9795e5519e7b31de6a3774966f8858964fc02 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1254,20 +1254,6 @@ static void get_ctx(struct perf_event_context *ctx)
        refcount_inc(&ctx->refcount);
 }
 
-static void *alloc_task_ctx_data(struct pmu *pmu)
-{
-       if (pmu->task_ctx_cache)
-               return kmem_cache_zalloc(pmu->task_ctx_cache, GFP_KERNEL);
-
-       return NULL;
-}
-
-static void free_task_ctx_data(struct pmu *pmu, void *task_ctx_data)
-{
-       if (pmu->task_ctx_cache && task_ctx_data)
-               kmem_cache_free(pmu->task_ctx_cache, task_ctx_data);
-}
-
 static void free_ctx(struct rcu_head *head)
 {
        struct perf_event_context *ctx;
@@ -3577,42 +3563,6 @@ static void perf_event_sync_stat(struct perf_event_context *ctx,
        }
 }
 
-#define double_list_for_each_entry(pos1, pos2, head1, head2, member)   \
-       for (pos1 = list_first_entry(head1, typeof(*pos1), member),     \
-            pos2 = list_first_entry(head2, typeof(*pos2), member);     \
-            !list_entry_is_head(pos1, head1, member) &&                \
-            !list_entry_is_head(pos2, head2, member);                  \
-            pos1 = list_next_entry(pos1, member),                      \
-            pos2 = list_next_entry(pos2, member))
-
-static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx,
-                                         struct perf_event_context *next_ctx)
-{
-       struct perf_event_pmu_context *prev_epc, *next_epc;
-
-       if (!prev_ctx->nr_task_data)
-               return;
-
-       double_list_for_each_entry(prev_epc, next_epc,
-                                  &prev_ctx->pmu_ctx_list, &next_ctx->pmu_ctx_list,
-                                  pmu_ctx_entry) {
-
-               if (WARN_ON_ONCE(prev_epc->pmu != next_epc->pmu))
-                       continue;
-
-               /*
-                * PMU specific parts of task perf context can require
-                * additional synchronization. As an example of such
-                * synchronization see implementation details of Intel
-                * LBR call stack data profiling;
-                */
-               if (prev_epc->pmu->swap_task_ctx)
-                       prev_epc->pmu->swap_task_ctx(prev_epc, next_epc);
-               else
-                       swap(prev_epc->task_ctx_data, next_epc->task_ctx_data);
-       }
-}
-
 static void perf_ctx_sched_task_cb(struct perf_event_context *ctx,
                                   struct task_struct *task, bool sched_in)
 {
@@ -3687,16 +3637,15 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
                        WRITE_ONCE(next_ctx->task, task);
 
                        perf_ctx_sched_task_cb(ctx, task, false);
-                       perf_event_swap_task_ctx_data(ctx, next_ctx);
 
                        perf_ctx_enable(ctx, false);
 
                        /*
                         * RCU_INIT_POINTER here is safe because we've not
                         * modified the ctx and the above modification of
-                        * ctx->task and ctx->task_ctx_data are immaterial
-                        * since those values are always verified under
-                        * ctx->lock which we're now holding.
+                        * ctx->task is immaterial since this value is
+                        * always verified under ctx->lock which we're now
+                        * holding.
                         */
                        RCU_INIT_POINTER(task->perf_event_ctxp, next_ctx);
                        RCU_INIT_POINTER(next->perf_event_ctxp, ctx);
@@ -5005,7 +4954,6 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
                     struct perf_event *event)
 {
        struct perf_event_pmu_context *new = NULL, *pos = NULL, *epc;
-       void *task_ctx_data = NULL;
 
        if (!ctx->task) {
                /*
@@ -5038,14 +4986,6 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
        if (!new)
                return ERR_PTR(-ENOMEM);
 
-       if (event->attach_state & PERF_ATTACH_TASK_DATA) {
-               task_ctx_data = alloc_task_ctx_data(pmu);
-               if (!task_ctx_data) {
-                       kfree(new);
-                       return ERR_PTR(-ENOMEM);
-               }
-       }
-
        __perf_init_event_pmu_context(new, pmu);
 
        /*
@@ -5080,14 +5020,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
        epc->ctx = ctx;
 
 found_epc:
-       if (task_ctx_data && !epc->task_ctx_data) {
-               epc->task_ctx_data = task_ctx_data;
-               task_ctx_data = NULL;
-               ctx->nr_task_data++;
-       }
        raw_spin_unlock_irq(&ctx->lock);
-
-       free_task_ctx_data(pmu, task_ctx_data);
        kfree(new);
 
        return epc;
@@ -5103,7 +5036,6 @@ static void free_cpc_rcu(struct rcu_head *head)
        struct perf_cpu_pmu_context *cpc =
                container_of(head, typeof(*cpc), epc.rcu_head);
 
-       kfree(cpc->epc.task_ctx_data);
        kfree(cpc);
 }
 
@@ -5111,7 +5043,6 @@ static void free_epc_rcu(struct rcu_head *head)
 {
        struct perf_event_pmu_context *epc = container_of(head, typeof(*epc), rcu_head);
 
-       kfree(epc->task_ctx_data);
        kfree(epc);
 }
 
@@ -14103,7 +14034,6 @@ inherit_event(struct perf_event *parent_event,
        if (is_orphaned_event(parent_event) ||
            !atomic_long_inc_not_zero(&parent_event->refcount)) {
                mutex_unlock(&parent_event->child_mutex);
-               /* task_ctx_data is freed with child_ctx */
                free_event(child_event);
                return NULL;
        }