--- /dev/null
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ Copyright (c) 2001, 2002, 2003 Eliot Dresselhaus
+
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ "Software"), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject to
+ the following conditions:
+
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include <vppinfra/longjmp.h>
+#include <vppinfra/mheap.h>
+#include <vppinfra/os.h>
+
+void clib_smp_free (clib_smp_main_t * m)
+{
+ clib_mem_vm_free (m->vm_base, (uword) ((1 + m->n_cpus) << m->log2_n_per_cpu_vm_bytes));
+}
+
+static uword allocate_per_cpu_mheap (uword cpu)
+{
+ clib_smp_main_t * m = &clib_smp_main;
+ void * heap;
+ uword vm_size, stack_size, mheap_flags;
+
+ ASSERT (os_get_cpu_number () == cpu);
+
+ vm_size = (uword) 1 << m->log2_n_per_cpu_vm_bytes;
+ stack_size = (uword) 1 << m->log2_n_per_cpu_stack_bytes;
+
+ mheap_flags = MHEAP_FLAG_SMALL_OBJECT_CACHE;
+
+ /* Heap extends up to start of stack. */
+ heap = mheap_alloc_with_flags (clib_smp_vm_base_for_cpu (m, cpu),
+ vm_size - stack_size,
+ mheap_flags);
+ clib_mem_set_heap (heap);
+
+ if (cpu == 0)
+ {
+ /* Now that we have a heap, allocate main structure on cpu 0. */
+ vec_resize (m->per_cpu_mains, m->n_cpus);
+
+ /* Allocate shared global heap (thread safe). */
+ m->global_heap =
+ mheap_alloc_with_flags (clib_smp_vm_base_for_cpu (m, cpu + m->n_cpus),
+ vm_size,
+ mheap_flags | MHEAP_FLAG_THREAD_SAFE);
+ }
+
+ m->per_cpu_mains[cpu].heap = heap;
+ return 0;
+}
+
+void clib_smp_init (void)
+{
+ clib_smp_main_t * m = &clib_smp_main;
+ uword cpu;
+
+ m->vm_base = clib_mem_vm_alloc ((uword) (m->n_cpus + 1) << m->log2_n_per_cpu_vm_bytes);
+ if (! m->vm_base)
+ clib_error ("error allocating virtual memory");
+
+ for (cpu = 0; cpu < m->n_cpus; cpu++)
+ clib_calljmp (allocate_per_cpu_mheap, cpu,
+ clib_smp_stack_top_for_cpu (m, cpu));
+}
+
+void clib_smp_lock_init (clib_smp_lock_t ** pl)
+{
+ clib_smp_lock_t * l;
+ uword i, n_bytes, n_fifo_elts;
+
+ /* No locking necessary if n_cpus <= 1.
+ Null means no locking is necessary. */
+ if (clib_smp_main.n_cpus < 2)
+ {
+ *pl = 0;
+ return;
+ }
+
+ /* Need n_cpus - 1 elts in waiting fifo. One CPU holds lock
+ and others could potentially be waiting. */
+ n_fifo_elts = clib_smp_main.n_cpus - 1;
+
+ n_bytes = sizeof (l[0]) + n_fifo_elts * sizeof (l->waiting_fifo[0]);
+ ASSERT_AND_PANIC (n_bytes % CLIB_CACHE_LINE_BYTES == 0);
+
+ l = clib_mem_alloc_aligned (n_bytes, CLIB_CACHE_LINE_BYTES);
+
+ memset (l, 0, n_bytes);
+ l->n_waiting_fifo_elts = n_fifo_elts;
+
+ for (i = 0; i < l->n_waiting_fifo_elts; i++)
+ l->waiting_fifo[i].wait_type = CLIB_SMP_LOCK_WAIT_EMPTY;
+
+ *pl = l;
+}
+
+void clib_smp_lock_free (clib_smp_lock_t ** pl)
+{
+ if (*pl)
+ clib_mem_free (*pl);
+ *pl = 0;
+}
+
+void clib_smp_lock_slow_path (clib_smp_lock_t * l,
+ uword my_cpu,
+ clib_smp_lock_header_t h0,
+ clib_smp_lock_type_t type)
+{
+ clib_smp_lock_header_t h1, h2, h3;
+ uword is_reader = type == CLIB_SMP_LOCK_TYPE_READER;
+ uword n_fifo_elts = l->n_waiting_fifo_elts;
+ uword my_tail;
+
+ /* Atomically advance waiting FIFO tail pointer; my_tail will point
+ to entry where we can insert ourselves to wait for lock to be granted. */
+ while (1)
+ {
+ h1 = h0;
+ my_tail = h1.waiting_fifo.head_index + h1.waiting_fifo.n_elts;
+ my_tail = my_tail >= n_fifo_elts ? my_tail - n_fifo_elts : my_tail;
+ h1.waiting_fifo.n_elts += 1;
+ h1.request_cpu = my_cpu;
+
+ ASSERT_AND_PANIC (h1.waiting_fifo.n_elts <= n_fifo_elts);
+ ASSERT_AND_PANIC (my_tail >= 0 && my_tail < n_fifo_elts);
+
+ h2 = clib_smp_lock_set_header (l, h1, h0);
+
+ /* Tail successfully advanced? */
+ if (clib_smp_lock_header_is_equal (h0, h2))
+ break;
+
+ /* It is possible that if head and tail are both zero, CPU with lock would have unlocked lock. */
+ else if (type == CLIB_SMP_LOCK_TYPE_SPIN)
+ {
+ while (! h2.writer_has_lock)
+ {
+ ASSERT_AND_PANIC (h2.waiting_fifo.n_elts == 0);
+ h1 = h2;
+ h1.request_cpu = my_cpu;
+ h1.writer_has_lock = 1;
+
+ h3 = clib_smp_lock_set_header (l, h1, h2);
+
+ /* Got it? */
+ if (clib_smp_lock_header_is_equal (h2, h3))
+ return;
+
+ h2 = h3;
+ }
+ }
+
+ /* Try to advance tail again. */
+ h0 = h2;
+ }
+
+ {
+ clib_smp_lock_waiting_fifo_elt_t * w;
+
+ w = l->waiting_fifo + my_tail;
+
+ while (w->wait_type != CLIB_SMP_LOCK_WAIT_EMPTY)
+ clib_smp_pause ();
+
+ w->wait_type = (is_reader
+ ? CLIB_SMP_LOCK_WAIT_READER
+ : CLIB_SMP_LOCK_WAIT_WRITER);
+
+ /* Wait until CPU holding the lock grants us the lock. */
+ while (w->wait_type != CLIB_SMP_LOCK_WAIT_DONE)
+ clib_smp_pause ();
+
+ w->wait_type = CLIB_SMP_LOCK_WAIT_EMPTY;
+ }
+}
+
+void clib_smp_unlock_slow_path (clib_smp_lock_t * l,
+ uword my_cpu,
+ clib_smp_lock_header_t h0,
+ clib_smp_lock_type_t type)
+{
+ clib_smp_lock_header_t h1, h2;
+ clib_smp_lock_waiting_fifo_elt_t * head;
+ clib_smp_lock_wait_type_t head_wait_type;
+ uword is_reader = type == CLIB_SMP_LOCK_TYPE_READER;
+ uword n_fifo_elts = l->n_waiting_fifo_elts;
+ uword head_index, must_wait_for_readers;
+
+ while (1)
+ {
+ /* Advance waiting fifo giving lock to first waiter. */
+ while (1)
+ {
+ ASSERT_AND_PANIC (h0.waiting_fifo.n_elts != 0);
+
+ h1 = h0;
+
+ head_index = h1.waiting_fifo.head_index;
+ head = l->waiting_fifo + head_index;
+ if (is_reader)
+ {
+ ASSERT_AND_PANIC (h1.n_readers_with_lock > 0);
+ h1.n_readers_with_lock -= 1;
+ }
+ else
+ {
+ /* Writer will already have lock. */
+ ASSERT_AND_PANIC (h1.writer_has_lock);
+ }
+
+ while ((head_wait_type = head->wait_type) == CLIB_SMP_LOCK_WAIT_EMPTY)
+ clib_smp_pause ();
+
+ /* Don't advance FIFO to writer unless all readers have unlocked. */
+ must_wait_for_readers =
+ (type != CLIB_SMP_LOCK_TYPE_SPIN
+ && head_wait_type == CLIB_SMP_LOCK_WAIT_WRITER
+ && h1.n_readers_with_lock != 0);
+
+ if (! must_wait_for_readers)
+ {
+ head_index += 1;
+ h1.waiting_fifo.n_elts -= 1;
+ if (type != CLIB_SMP_LOCK_TYPE_SPIN)
+ {
+ if (head_wait_type == CLIB_SMP_LOCK_WAIT_WRITER)
+ h1.writer_has_lock = h1.n_readers_with_lock == 0;
+ else
+ {
+ h1.writer_has_lock = 0;
+ h1.n_readers_with_lock += 1;
+ }
+ }
+ }
+
+ h1.waiting_fifo.head_index = head_index == n_fifo_elts ? 0 : head_index;
+ h1.request_cpu = my_cpu;
+
+ ASSERT_AND_PANIC (h1.waiting_fifo.head_index >= 0 && h1.waiting_fifo.head_index < n_fifo_elts);
+ ASSERT_AND_PANIC (h1.waiting_fifo.n_elts >= 0 && h1.waiting_fifo.n_elts <= n_fifo_elts);
+
+ h2 = clib_smp_lock_set_header (l, h1, h0);
+
+ if (clib_smp_lock_header_is_equal (h2, h0))
+ break;
+
+ h0 = h2;
+
+ if (h0.waiting_fifo.n_elts == 0)
+ return clib_smp_unlock_inline (l, type);
+ }
+
+ if (must_wait_for_readers)
+ return;
+
+ /* Wake up head of waiting fifo. */
+ {
+ uword done_waking;
+
+ /* Shift lock to first thread waiting in fifo. */
+ head->wait_type = CLIB_SMP_LOCK_WAIT_DONE;
+
+ /* For read locks we may be able to wake multiple readers. */
+ done_waking = 1;
+ if (head_wait_type == CLIB_SMP_LOCK_WAIT_READER)
+ {
+ uword hi = h0.waiting_fifo.head_index;
+ if (h0.waiting_fifo.n_elts != 0
+ && l->waiting_fifo[hi].wait_type == CLIB_SMP_LOCK_WAIT_READER)
+ done_waking = 0;
+ }
+
+ if (done_waking)
+ break;
+ }
+ }
+}
Code Review / vpp.git / blobdiff