mm/mmap_lock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define CREATE_TRACE_POINTS
   3 #include <trace/events/mmap_lock.h>
   4
   5 #include <linux/mm.h>
   6 #include <linux/cgroup.h>
   7 #include <linux/memcontrol.h>
   8 #include <linux/mmap_lock.h>
   9 #include <linux/mutex.h>
  10 #include <linux/percpu.h>
  11 #include <linux/rcupdate.h>
  12 #include <linux/smp.h>
  13 #include <linux/trace_events.h>
  14 #include <linux/local_lock.h>
  15
  16 EXPORT_TRACEPOINT_SYMBOL(mmap_lock_start_locking);
  17 EXPORT_TRACEPOINT_SYMBOL(mmap_lock_acquire_returned);
  18 EXPORT_TRACEPOINT_SYMBOL(mmap_lock_released);
  19
  20 #ifdef CONFIG_MEMCG
  21
  22 /*
  23  * Size of the buffer for memcg path names. Ignoring stack trace support,
  24  * trace_events_hist.c uses MAX_FILTER_STR_VAL for this, so we also use it.
  25  */
  26 #define MEMCG_PATH_BUF_SIZE MAX_FILTER_STR_VAL
  27
  28 #define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                            \
  29         do {                                                            \
  30                 if (trace_mmap_lock_##type##_enabled()) {               \
  31                         char buf[MEMCG_PATH_BUF_SIZE];                  \
  32                         get_mm_memcg_path(mm, buf, sizeof(buf));        \
  33                         trace_mmap_lock_##type(mm, buf, ##__VA_ARGS__); \
  34                 }                                                       \
  35         } while (0)
  36
  37 #else /* !CONFIG_MEMCG */
  38
  39 #define TRACE_MMAP_LOCK_EVENT(type, mm, ...)                                   \
  40         trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
  41
  42 #endif /* CONFIG_MEMCG */
  43
  44 #ifdef CONFIG_TRACING
  45 #ifdef CONFIG_MEMCG
  46 /*
  47  * Write the given mm_struct's memcg path to a buffer. If the path cannot be
  48  * determined, empty string is written.
  49  */
  50 static void get_mm_memcg_path(struct mm_struct *mm, char *buf, size_t buflen)
  51 {
  52         struct mem_cgroup *memcg;
  53
  54         buf[0] = '\0';
  55         memcg = get_mem_cgroup_from_mm(mm);
  56         if (memcg == NULL)
  57                 return;
  58         if (memcg->css.cgroup)
  59                 cgroup_path(memcg->css.cgroup, buf, buflen);
  60         css_put(&memcg->css);
  61 }
  62
  63 #endif /* CONFIG_MEMCG */
  64
  65 /*
  66  * Trace calls must be in a separate file, as otherwise there's a circular
  67  * dependency between linux/mmap_lock.h and trace/events/mmap_lock.h.
  68  */
  69
  70 void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write)
  71 {
  72         TRACE_MMAP_LOCK_EVENT(start_locking, mm, write);
  73 }
  74 EXPORT_SYMBOL(__mmap_lock_do_trace_start_locking);
  75
  76 void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write,
  77                                            bool success)
  78 {
  79         TRACE_MMAP_LOCK_EVENT(acquire_returned, mm, write, success);
  80 }
  81 EXPORT_SYMBOL(__mmap_lock_do_trace_acquire_returned);
  82
  83 void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write)
  84 {
  85         TRACE_MMAP_LOCK_EVENT(released, mm, write);
  86 }
  87 EXPORT_SYMBOL(__mmap_lock_do_trace_released);
  88 #endif /* CONFIG_TRACING */