drm/amdkfd: Simplify event ID and signal slot management

Signal slots are identical to event IDs.

Replace the used_slot_bitmap and events hash table with an IDR to
allocate and lookup event IDs and signal slots more efficiently.
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

drivers/gpu/drm/amd/amdkfd/kfd_events.h

@@ -31,9 +31,13 @@
 #include "kfd_priv.h"
 #include <uapi/linux/kfd_ioctl.h>
 
-#define KFD_EVENT_ID_NONSIGNAL_MASK 0x80000000U
-#define KFD_FIRST_NONSIGNAL_EVENT_ID KFD_EVENT_ID_NONSIGNAL_MASK
-#define KFD_LAST_NONSIGNAL_EVENT_ID UINT_MAX
+/*
+ * IDR supports non-negative integer IDs. Small IDs are used for
+ * signal events to match their signal slot. Use the upper half of the
+ * ID space for non-signal events.
+ */
+#define KFD_FIRST_NONSIGNAL_EVENT_ID ((INT_MAX >> 1) + 1)
+#define KFD_LAST_NONSIGNAL_EVENT_ID INT_MAX
 
 /*
  * Written into kfd_signal_slot_t to indicate that the event is not signaled.
@@ -47,9 +51,6 @@ struct kfd_event_waiter;
 struct signal_page;
 
 struct kfd_event {
-	/* All events in process, rooted at kfd_process.events. */
-	struct hlist_node events;
-
 	u32 event_id;
 
 	bool signaled;
@@ -60,7 +61,6 @@ struct kfd_event {
 	wait_queue_head_t wq; /* List of event waiters. */
 
 	/* Only for signal events. */
-	unsigned int signal_slot_index;
 	uint64_t __user *user_signal_address;
 
 	/* type specific data */

drivers/gpu/drm/amd/amdkfd/kfd_priv.h

@@ -31,6 +31,7 @@
 #include <linux/workqueue.h>
 #include <linux/spinlock.h>
 #include <linux/kfd_ioctl.h>
+#include <linux/idr.h>
 #include <kgd_kfd_interface.h>
 
 #include "amd_shared.h"
@@ -538,11 +539,10 @@ struct kfd_process {
 
 	/* Event-related data */
 	struct mutex event_mutex;
-	/* All events in process hashed by ID, linked on kfd_event.events. */
-	DECLARE_HASHTABLE(events, 4);
+	/* Event ID allocator and lookup */
+	struct idr event_idr;
 	/* Event page */
 	struct kfd_signal_page *signal_page;
-	u32 next_nonsignal_event_id;
 	size_t signal_event_count;
 	bool signal_event_limit_reached;
 };