#include <linux/sched.h>
#include <linux/seq_file.h>
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+#include <linux/stackdepot.h>
+#include <linux/sort.h>
+#include <linux/timekeeping.h>
+#include <linux/math64.h>
+#endif
+
#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_dp_mst_helper.h>
}
EXPORT_SYMBOL(drm_dp_mst_put_port_malloc);
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+
+#define STACK_DEPTH 8
+
+static noinline void
+__topology_ref_save(struct drm_dp_mst_topology_mgr *mgr,
+ struct drm_dp_mst_topology_ref_history *history,
+ enum drm_dp_mst_topology_ref_type type)
+{
+ struct drm_dp_mst_topology_ref_entry *entry = NULL;
+ depot_stack_handle_t backtrace;
+ ulong stack_entries[STACK_DEPTH];
+ uint n;
+ int i;
+
+ n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1);
+ backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL);
+ if (!backtrace)
+ return;
+
+ /* Try to find an existing entry for this backtrace */
+ for (i = 0; i < history->len; i++) {
+ if (history->entries[i].backtrace == backtrace) {
+ entry = &history->entries[i];
+ break;
+ }
+ }
+
+ /* Otherwise add one */
+ if (!entry) {
+ struct drm_dp_mst_topology_ref_entry *new;
+ int new_len = history->len + 1;
+
+ new = krealloc(history->entries, sizeof(*new) * new_len,
+ GFP_KERNEL);
+ if (!new)
+ return;
+
+ entry = &new[history->len];
+ history->len = new_len;
+ history->entries = new;
+
+ entry->backtrace = backtrace;
+ entry->type = type;
+ entry->count = 0;
+ }
+ entry->count++;
+ entry->ts_nsec = ktime_get_ns();
+}
+
+static int
+topology_ref_history_cmp(const void *a, const void *b)
+{
+ const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b;
+
+ if (entry_a->ts_nsec > entry_b->ts_nsec)
+ return 1;
+ else if (entry_a->ts_nsec < entry_b->ts_nsec)
+ return -1;
+ else
+ return 0;
+}
+
+static inline const char *
+topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type)
+{
+ if (type == DRM_DP_MST_TOPOLOGY_REF_GET)
+ return "get";
+ else
+ return "put";
+}
+
+static void
+__dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history,
+ void *ptr, const char *type_str)
+{
+ struct drm_printer p = drm_debug_printer(DBG_PREFIX);
+ char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ int i;
+
+ if (!buf)
+ return;
+
+ if (!history->len)
+ goto out;
+
+ /* First, sort the list so that it goes from oldest to newest
+ * reference entry
+ */
+ sort(history->entries, history->len, sizeof(*history->entries),
+ topology_ref_history_cmp, NULL);
+
+ drm_printf(&p, "%s (%p) topology count reached 0, dumping history:\n",
+ type_str, ptr);
+
+ for (i = 0; i < history->len; i++) {
+ const struct drm_dp_mst_topology_ref_entry *entry =
+ &history->entries[i];
+ ulong *entries;
+ uint nr_entries;
+ u64 ts_nsec = entry->ts_nsec;
+ u64 rem_nsec = do_div(ts_nsec, 1000000000);
+
+ nr_entries = stack_depot_fetch(entry->backtrace, &entries);
+ stack_trace_snprint(buf, PAGE_SIZE, entries, nr_entries, 4);
+
+ drm_printf(&p, " %d %ss (last at %5llu.%06llu):\n%s",
+ entry->count,
+ topology_ref_type_to_str(entry->type),
+ ts_nsec, rem_nsec / 1000, buf);
+ }
+
+ /* Now free the history, since this is the only time we expose it */
+ kfree(history->entries);
+out:
+ kfree(buf);
+}
+
+static __always_inline void
+drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb)
+{
+ __dump_topology_ref_history(&mstb->topology_ref_history, mstb,
+ "MSTB");
+}
+
+static __always_inline void
+drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port)
+{
+ __dump_topology_ref_history(&port->topology_ref_history, port,
+ "Port");
+}
+
+static __always_inline void
+save_mstb_topology_ref(struct drm_dp_mst_branch *mstb,
+ enum drm_dp_mst_topology_ref_type type)
+{
+ __topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type);
+}
+
+static __always_inline void
+save_port_topology_ref(struct drm_dp_mst_port *port,
+ enum drm_dp_mst_topology_ref_type type)
+{
+ __topology_ref_save(port->mgr, &port->topology_ref_history, type);
+}
+
+static inline void
+topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr)
+{
+ mutex_lock(&mgr->topology_ref_history_lock);
+}
+
+static inline void
+topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr)
+{
+ mutex_unlock(&mgr->topology_ref_history_lock);
+}
+#else
+static inline void
+topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {}
+static inline void
+topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {}
+static inline void
+drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {}
+static inline void
+drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {}
+#define save_mstb_topology_ref(mstb, type)
+#define save_port_topology_ref(port, type)
+#endif
+
static void drm_dp_destroy_mst_branch_device(struct kref *kref)
{
struct drm_dp_mst_branch *mstb =
container_of(kref, struct drm_dp_mst_branch, topology_kref);
struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
+ drm_dp_mst_dump_mstb_topology_history(mstb);
+
INIT_LIST_HEAD(&mstb->destroy_next);
/*
static int __must_check
drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb)
{
- int ret = kref_get_unless_zero(&mstb->topology_kref);
+ int ret;
- if (ret)
- DRM_DEBUG("mstb %p (%d)\n", mstb,
- kref_read(&mstb->topology_kref));
+ topology_ref_history_lock(mstb->mgr);
+ ret = kref_get_unless_zero(&mstb->topology_kref);
+ if (ret) {
+ DRM_DEBUG("mstb %p (%d)\n",
+ mstb, kref_read(&mstb->topology_kref));
+ save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
+ }
+
+ topology_ref_history_unlock(mstb->mgr);
return ret;
}
*/
static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb)
{
+ topology_ref_history_lock(mstb->mgr);
+
+ save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
WARN_ON(kref_read(&mstb->topology_kref) == 0);
kref_get(&mstb->topology_kref);
DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
+
+ topology_ref_history_unlock(mstb->mgr);
}
/**
static void
drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb)
{
+ topology_ref_history_lock(mstb->mgr);
+
DRM_DEBUG("mstb %p (%d)\n",
mstb, kref_read(&mstb->topology_kref) - 1);
+ save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT);
+
+ topology_ref_history_unlock(mstb->mgr);
kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device);
}
container_of(kref, struct drm_dp_mst_port, topology_kref);
struct drm_dp_mst_topology_mgr *mgr = port->mgr;
+ drm_dp_mst_dump_port_topology_history(port);
+
/* There's nothing that needs locking to destroy an input port yet */
if (port->input) {
drm_dp_mst_put_port_malloc(port);
static int __must_check
drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port)
{
- int ret = kref_get_unless_zero(&port->topology_kref);
+ int ret;
- if (ret)
- DRM_DEBUG("port %p (%d)\n", port,
- kref_read(&port->topology_kref));
+ topology_ref_history_lock(port->mgr);
+ ret = kref_get_unless_zero(&port->topology_kref);
+ if (ret) {
+ DRM_DEBUG("port %p (%d)\n",
+ port, kref_read(&port->topology_kref));
+ save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
+ }
+ topology_ref_history_unlock(port->mgr);
return ret;
}
*/
static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
{
+ topology_ref_history_lock(port->mgr);
+
WARN_ON(kref_read(&port->topology_kref) == 0);
kref_get(&port->topology_kref);
DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->topology_kref));
+ save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
+
+ topology_ref_history_unlock(port->mgr);
}
/**
*/
static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
{
+ topology_ref_history_lock(port->mgr);
+
DRM_DEBUG("port %p (%d)\n",
port, kref_read(&port->topology_kref) - 1);
+ save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT);
+
+ topology_ref_history_unlock(port->mgr);
kref_put(&port->topology_kref, drm_dp_destroy_port);
}
mutex_init(&mgr->delayed_destroy_lock);
mutex_init(&mgr->up_req_lock);
mutex_init(&mgr->probe_lock);
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+ mutex_init(&mgr->topology_ref_history_lock);
+#endif
INIT_LIST_HEAD(&mgr->tx_msg_downq);
INIT_LIST_HEAD(&mgr->destroy_port_list);
INIT_LIST_HEAD(&mgr->destroy_branch_device_list);
mutex_destroy(&mgr->lock);
mutex_destroy(&mgr->up_req_lock);
mutex_destroy(&mgr->probe_lock);
+#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
+ mutex_destroy(&mgr->topology_ref_history_lock);
+#endif
}
EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
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