[host] add ability to double defrag buffers when running out of buffers

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

libknet/threads_rx.c

@@ -10,6 +10,7 @@
 #include "config.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <sys/uio.h>
@@ -60,17 +61,66 @@ static inline int _timecmp(struct timespec a, struct timespec b)
 }
 
 /*
- * this functions needs to return an index (0 to 7)
+ * check if we can double the defrag buffers.
+ *
+ * return 0 if we cannot reallocate
+ * return 1 if we have more buffers
+ */
+
+static int _realloc_defrag_buffers(knet_handle_t knet_h, struct knet_host *src_host)
+{
+	struct knet_host_defrag_buf *new_bufs = NULL;
+	int i;
+
+	/*
+	 * max_defrag_bufs is a power of 2
+	 * allocated_defrag_bufs doubles on each iteraction.
+	 * Sooner or later (and hopefully never) allocated with be == to max.
+	 */
+	if (src_host->allocated_defrag_bufs < knet_h->max_defrag_bufs) {
+		new_bufs = realloc(src_host->defrag_bufs,
+				   src_host->allocated_defrag_bufs * 2 * sizeof(struct knet_host_defrag_buf));
+		if (!new_bufs) {
+			log_err(knet_h, KNET_SUB_RX, "Unable to increase defrag buffers for host %u: %s",
+				src_host->host_id, strerror(errno));
+			return 0;
+		}
+
+		/*
+		 * keep the math simple here between arrays, pointers and what not.
+		 * Init each buffer individually.
+		 */
+		for (i = src_host->allocated_defrag_bufs; i < src_host->allocated_defrag_bufs * 2; i++) {
+			memset(&new_bufs[i], 0, sizeof(struct knet_host_defrag_buf));
+		}
+
+		src_host->allocated_defrag_bufs = src_host->allocated_defrag_bufs * 2;
+
+		src_host->defrag_bufs = new_bufs;
+
+		log_debug(knet_h, KNET_SUB_RX, "Defrag buffers for host %u increased from %u to: %u",
+			  src_host->host_id, src_host->allocated_defrag_bufs / 2, src_host->allocated_defrag_bufs);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * this functions needs to return an index
  * to a knet_host_defrag_buf. (-1 on errors)
  */
 
 static int _find_pckt_defrag_buf(knet_handle_t knet_h, struct knet_host *src_host, seq_num_t seq_num)
 {
 	int i, oldest;
+	uint16_t cur_allocated_defrag_bufs = src_host->allocated_defrag_bufs;
 
 	/*
 	 * check if there is a buffer already in use handling the same seq_num
 	 */
+
 	for (i = 0; i < src_host->allocated_defrag_bufs; i++) {
 		if (src_host->defrag_bufs[i].in_use) {
 			if (src_host->defrag_bufs[i].pckt_seq == seq_num) {
@@ -86,6 +136,7 @@ static int _find_pckt_defrag_buf(knet_handle_t knet_h, struct knet_host *src_hos
 	 * buffer. If the pckt has been seen before, the buffer expired (ETIME)
 	 * and there is no point to try to defrag it again.
 	 */
+
 	if (!_seq_num_lookup(knet_h, src_host, seq_num, 1, 0)) {
 		errno = ETIME;
 		return -1;
@@ -94,17 +145,27 @@ static int _find_pckt_defrag_buf(knet_handle_t knet_h, struct knet_host *src_hos
 	/*
 	 * register the pckt as seen
 	 */
+
 	_seq_num_set(src_host, seq_num, 1);
 
 	/*
 	 * see if there is a free buffer
 	 */
+
 	for (i = 0; i < src_host->allocated_defrag_bufs; i++) {
 		if (!src_host->defrag_bufs[i].in_use) {
 			return i;
 		}
 	}
 
+	/*
+	 * check if we can increase num of buffers
+	 */
+
+	if (_realloc_defrag_buffers(knet_h, src_host)) {
+		return cur_allocated_defrag_bufs + 1;
+	}
+
 	/*
 	 * at this point, there are no free buffers, the pckt is new
 	 * and we need to reclaim a buffer, and we will take the one
@@ -119,6 +180,7 @@ static int _find_pckt_defrag_buf(knet_handle_t knet_h, struct knet_host *src_hos
 		}
 	}
 	src_host->defrag_bufs[oldest].in_use = 0;
+
 	return oldest;
 }