vppinfra: refactor interrupt code

Type: improvement
Change-Id: Ie6987736faf7d8a641762e276775da8ee0c03ea4
Signed-off-by: Damjan Marion <damarion@cisco.com>

4 files changed, 112 insertions, 138 deletions

diff --git a/src/vppinfra/CMakeLists.txt b/src/vppinfra/CMakeLists.txt
index 46b2788ddfd..d64847161bd 100644
--- a/src/vppinfra/CMakeLists.txt
+++ b/src/vppinfra/CMakeLists.txt
@@ -249,6 +249,7 @@ if(VPP_BUILD_VPPINFRA_TESTS)
     fpool
     hash
     heap
+    interrupt
     longjmp
     macros
     maplog
diff --git a/src/vppinfra/interrupt.c b/src/vppinfra/interrupt.c
index df242d932b6..c9f0078c5e4 100644
--- a/src/vppinfra/interrupt.c
+++ b/src/vppinfra/interrupt.c
@@ -1,42 +1,33 @@
-
-/*
- * Copyright (c) 2020 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.
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2023 Cisco Systems, Inc.
  */
 
 #include <vppinfra/clib.h>
-#include <vppinfra/vec.h>
 #include <vppinfra/interrupt.h>
-#include <vppinfra/format.h>
 
 __clib_export void
-clib_interrupt_init (void **data, uword n_int)
+clib_interrupt_init (void **data, u32 n_int)
 {
   clib_interrupt_header_t *h;
-  uword sz = sizeof (clib_interrupt_header_t);
-  uword data_size = round_pow2 (n_int, CLIB_CACHE_LINE_BYTES * 8) / 8;
+  const u32 bits_in_cl = 8 << CLIB_LOG2_CACHE_LINE_BYTES;
+  u32 sz = sizeof (clib_interrupt_header_t);
+  u32 n_cl = round_pow2 (n_int, bits_in_cl) / bits_in_cl;
 
-  sz += 2 * data_size;
+  sz += 2 * n_cl * CLIB_CACHE_LINE_BYTES;
   h = data[0] = clib_mem_alloc_aligned (sz, CLIB_CACHE_LINE_BYTES);
   clib_memset (data[0], 0, sz);
   h->n_int = n_int;
-  h->n_uword_alloc = (data_size * 8) >> log2_uword_bits;
+  h->uwords_allocated = n_cl * bits_in_cl / uword_bits;
+  h->uwords_used = round_pow2 (n_int, uword_bits) / uword_bits;
+  h->local = (uword *) (h + 1);
+  h->remote = h->local + h->uwords_allocated;
 }
 
 __clib_export void
-clib_interrupt_resize (void **data, uword n_int)
+clib_interrupt_resize (void **data, u32 n_int)
 {
   clib_interrupt_header_t *h = data[0];
+  u32 new_n_uwords, i;
 
   if (data[0] == 0)
     {
@@ -44,48 +35,37 @@ clib_interrupt_resize (void **data, uword n_int)
       return;
     }
 
-  if (n_int < h->n_int)
+  if (n_int == h->n_int)
+    return;
+
+  new_n_uwords = round_pow2 (n_int, uword_bits) / uword_bits;
+
+  if (new_n_uwords > h->uwords_allocated)
     {
-      uword *old_bmp, *old_abp, v;
-      old_bmp = clib_interrupt_get_bitmap (data[0]);
-      old_abp = clib_interrupt_get_atomic_bitmap (data[0]);
-      for (uword i = 0; i < h->n_uword_alloc; i++)
-	{
-	  v = old_abp[i];
-	  old_abp[i] = 0;
-	  if (n_int > ((i + 1) * uword_bits))
-	    old_bmp[i] |= v;
-	  else if (n_int > (i * uword_bits))
-	    old_bmp[i] = (old_bmp[i] | v) & pow2_mask (n_int - i * uword_bits);
-	  else
-	    old_bmp[i] = 0;
-	}
+      clib_interrupt_header_t *nh;
+      clib_interrupt_init ((void **) &nh, n_int);
+      for (int i = 0; i < h->uwords_used; i++)
+	nh->local[i] = h->local[i] | h->remote[i];
+      clib_mem_free (data[0]);
+      data[0] = nh;
+      return;
     }
-  else if (n_int > h->n_uword_alloc * uword_bits)
-    {
-      void *old = data[0];
-      uword *old_bmp, *old_abp, *new_bmp;
-      uword n_uwords = round_pow2 (h->n_int, uword_bits) / uword_bits;
 
-      clib_interrupt_init (data, n_int);
-      h = data[0];
+  h->n_int = n_int;
+  h->uwords_used = new_n_uwords;
 
-      new_bmp = clib_interrupt_get_bitmap (data[0]);
-      old_bmp = clib_interrupt_get_bitmap (old);
-      old_abp = clib_interrupt_get_atomic_bitmap (old);
+  for (i = 0; i < new_n_uwords; i++)
+    h->local[i] |= h->remote[i];
 
-      for (uword i = 0; i < n_uwords; i++)
-	new_bmp[i] = old_bmp[i] | old_abp[i];
+  for (i = 0; i < h->uwords_allocated; i++)
+    h->remote[i] = 0;
 
-      clib_mem_free (old);
-    }
-  h->n_int = n_int;
+  for (i = new_n_uwords; i < h->uwords_allocated; i++)
+    h->local[i] = 0;
+
+  n_int &= pow2_mask (log2_uword_bits);
+
+  if (n_int)
+    h->local[n_int >> log2_uword_bits] &= pow2_mask (n_int);
 }
 
-/*
- * fd.io coding-style-patch-verification: ON
- *
- * Local Variables:
- * eval: (c-set-style "gnu")
- * End:
- */
diff --git a/src/vppinfra/interrupt.h b/src/vppinfra/interrupt.h
index 5c39b2183f8..b0d7dde272a 100644
--- a/src/vppinfra/interrupt.h
+++ b/src/vppinfra/interrupt.h
@@ -1,16 +1,5 @@
-/*
- * Copyright (c) 2020 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.
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2023 Cisco Systems, Inc.
  */
 
 #ifndef included_clib_interrupt_h
@@ -22,12 +11,15 @@
 typedef struct
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
-  int n_int;
-  uword n_uword_alloc;
+  u32 n_int;
+  u32 uwords_allocated;
+  u32 uwords_used;
+  uword *local;
+  uword *remote;
 } clib_interrupt_header_t;
 
-void clib_interrupt_init (void **data, uword n_interrupts);
-void clib_interrupt_resize (void **data, uword n_interrupts);
+void clib_interrupt_init (void **data, u32 n_interrupts);
+void clib_interrupt_resize (void **data, u32 n_interrupts);
 
 static_always_inline void
 clib_interrupt_free (void **data)
@@ -48,96 +40,98 @@ clib_interrupt_get_n_int (void *d)
   return 0;
 }
 
-static_always_inline uword *
-clib_interrupt_get_bitmap (void *d)
-{
-  return d + sizeof (clib_interrupt_header_t);
-}
-
-static_always_inline uword *
-clib_interrupt_get_atomic_bitmap (void *d)
-{
-  clib_interrupt_header_t *h = d;
-  return clib_interrupt_get_bitmap (d) + h->n_uword_alloc;
-}
-
 static_always_inline void
 clib_interrupt_set (void *in, int int_num)
 {
-  uword *bmp = clib_interrupt_get_bitmap (in);
-  uword mask = 1ULL << (int_num & (uword_bits - 1));
-  bmp += int_num >> log2_uword_bits;
+  clib_interrupt_header_t *h = in;
+  u32 off = int_num >> log2_uword_bits;
+  uword bit = 1ULL << (int_num & pow2_mask (log2_uword_bits));
 
-  ASSERT (int_num < ((clib_interrupt_header_t *) in)->n_int);
+  ASSERT (int_num < h->n_int);
 
-  *bmp |= mask;
+  h->local[off] |= bit;
 }
 
 static_always_inline void
 clib_interrupt_set_atomic (void *in, int int_num)
 {
-  uword *bmp = clib_interrupt_get_atomic_bitmap (in);
-  uword mask = 1ULL << (int_num & (uword_bits - 1));
-  bmp += int_num >> log2_uword_bits;
+  clib_interrupt_header_t *h = in;
+  u32 off = int_num >> log2_uword_bits;
+  uword bit = 1ULL << (int_num & pow2_mask (log2_uword_bits));
 
-  ASSERT (int_num < ((clib_interrupt_header_t *) in)->n_int);
+  ASSERT (int_num < h->n_int);
 
-  __atomic_fetch_or (bmp, mask, __ATOMIC_RELAXED);
+  __atomic_fetch_or (h->remote + off, bit, __ATOMIC_RELAXED);
 }
 
 static_always_inline void
 clib_interrupt_clear (void *in, int int_num)
 {
-  uword *bmp = clib_interrupt_get_bitmap (in);
-  uword *abm = clib_interrupt_get_atomic_bitmap (in);
-  uword mask = 1ULL << (int_num & (uword_bits - 1));
-  uword off = int_num >> log2_uword_bits;
+  clib_interrupt_header_t *h = in;
+  u32 off = int_num >> log2_uword_bits;
+  uword bit = 1ULL << (int_num & pow2_mask (log2_uword_bits));
+  uword *loc = h->local;
+  uword *rem = h->remote;
+  uword v;
 
-  ASSERT (int_num < ((clib_interrupt_header_t *) in)->n_int);
+  ASSERT (int_num < h->n_int);
 
-  bmp[off] |= __atomic_exchange_n (abm + off, 0, __ATOMIC_SEQ_CST);
-  bmp[off] &= ~mask;
+  v = loc[off] | __atomic_exchange_n (rem + off, 0, __ATOMIC_SEQ_CST);
+  loc[off] = v & ~bit;
 }
 
 static_always_inline int
-clib_interrupt_get_next (void *in, int last)
+clib_interrupt_get_next_and_clear (void *in, int last)
 {
-  uword *bmp = clib_interrupt_get_bitmap (in);
-  uword *abm = clib_interrupt_get_atomic_bitmap (in);
   clib_interrupt_header_t *h = in;
-  uword bmp_uword, off;
+  uword bit, v;
+  uword *loc = h->local;
+  uword *rem = h->remote;
+  u32 off, n_uwords = h->uwords_used;
 
-  ASSERT (last >= -1 && last < h->n_int);
+  ASSERT (last >= -1 && last < (int) h->n_int);
 
   off = (last + 1) >> log2_uword_bits;
-  if (off > h->n_int >> log2_uword_bits || off >= h->n_uword_alloc)
+
+  if (off >= n_uwords)
     return -1;
 
-  last -= off << log2_uword_bits;
-  bmp[off] |= __atomic_exchange_n (abm + off, 0, __ATOMIC_SEQ_CST);
-  bmp_uword = bmp[off] & ~pow2_mask (last + 1);
+  v = loc[off] | __atomic_exchange_n (rem + off, 0, __ATOMIC_SEQ_CST);
+  loc[off] = v;
+
+  v &= ~pow2_mask ((last + 1) & pow2_mask (log2_uword_bits));
 
-next:
-  if (bmp_uword)
-    return (off << log2_uword_bits) + count_trailing_zeros (bmp_uword);
+  while (v == 0)
+    {
+      if (++off == n_uwords)
+	return -1;
 
-  off++;
+      v = loc[off] | __atomic_exchange_n (rem + off, 0, __ATOMIC_SEQ_CST);
+      loc[off] = v;
+    }
 
-  if (off > h->n_int >> log2_uword_bits || off >= h->n_uword_alloc)
-    return -1;
+  bit = get_lowest_set_bit (v);
+  loc[off] &= ~bit;
+  return get_lowest_set_bit_index (bit) + (int) (off << log2_uword_bits);
+}
+
+static_always_inline int
+clib_interrupt_is_any_pending (void *in)
+{
+  clib_interrupt_header_t *h = in;
+  u32 n_uwords = h->uwords_used;
+  uword *loc = h->local;
+  uword *rem = h->remote;
+
+  for (u32 i = 0; i < n_uwords; i++)
+    if (loc[i])
+      return 1;
 
-  bmp[off] |= __atomic_exchange_n (abm + off, 0, __ATOMIC_SEQ_CST);
-  bmp_uword = bmp[off];
+  for (u32 i = 0; i < n_uwords; i++)
+    if (rem[i])
+      return 1;
 
-  goto next;
+  return 0;
 }
 
 #endif /* included_clib_interrupt_h */
-
-/*
- * fd.io coding-style-patch-verification: ON
- *
- * Local Variables:
- * eval: (c-set-style "gnu")
- * End:
- */
diff --git a/src/vppinfra/test_interrupt.c b/src/vppinfra/test_interrupt.c
index 519805edc89..133692d1bd0 100644
--- a/src/vppinfra/test_interrupt.c
+++ b/src/vppinfra/test_interrupt.c
@@ -33,10 +33,7 @@ int debug = 0;
 void
 set_and_check_bits (void *interrupts, int num_ints)
 {
-
-  int step;
-
-  for (step = 1; step < num_ints; step++)
+  for (int step = 1; step < num_ints; step++)
     {
       int int_num = -1;
       int expected = 0;
@@ -48,13 +45,15 @@ set_and_check_bits (void *interrupts, int num_ints)
 	  clib_interrupt_set (interrupts, i);
 	}
 
-      while ((int_num = clib_interrupt_get_next (interrupts, int_num)) != -1)
+      while ((int_num =
+		clib_interrupt_get_next_and_clear (interrupts, int_num)) != -1)
 	{
 	  debug ("    Got %d, expecting %d\n", int_num, expected);
 	  ASSERT (int_num == expected);
 	  expected += step;
-	  clib_interrupt_clear (interrupts, int_num);
 	}
+      int_num = clib_interrupt_get_next_and_clear (interrupts, -1);
+      ASSERT (int_num == -1);
     }
 }