X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=lib%2Flibrte_eal%2Fcommon%2Feal_common_fbarray.c;h=b7ddb66e9ca39cfae4236128071fe5f21b52aff6;hb=cfe3aeb170b2f6277e6f96173599da51eab0654f;hp=d17611b57f32a697b8febe006de4bcb928974c18;hpb=f9a4f1b4623a8f6673a15670c314be18c0efe623;p=dpdk.git

diff --git a/lib/librte_eal/common/eal_common_fbarray.c b/lib/librte_eal/common/eal_common_fbarray.c
index d17611b57f..b7ddb66e9c 100644
--- a/lib/librte_eal/common/eal_common_fbarray.c
+++ b/lib/librte_eal/common/eal_common_fbarray.c
@@ -2,6 +2,7 @@
  * Copyright(c) 2017-2018 Intel Corporation
  */
 
+#include <fcntl.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <sys/mman.h>
@@ -27,6 +28,22 @@
 #define MASK_LEN_TO_MOD(x) ((x) - RTE_ALIGN_FLOOR(x, MASK_ALIGN))
 #define MASK_GET_IDX(idx, mod) ((idx << MASK_SHIFT) + mod)
 
+/*
+ * We use this to keep track of created/attached memory areas to prevent user
+ * errors in API usage.
+ */
+struct mem_area {
+	TAILQ_ENTRY(mem_area) next;
+	void *addr;
+	size_t len;
+	int fd;
+};
+TAILQ_HEAD(mem_area_head, mem_area);
+/* local per-process tailq */
+static struct mem_area_head mem_area_tailq =
+	TAILQ_HEAD_INITIALIZER(mem_area_tailq);
+static rte_spinlock_t mem_area_lock = RTE_SPINLOCK_INITIALIZER;
+
 /*
  * This is a mask that is always stored at the end of array, to provide fast
  * way of finding free/used spots without looping through each element.
@@ -86,6 +103,22 @@ resize_and_map(int fd, void *addr, size_t len)
 	return 0;
 }
 
+static int
+overlap(const struct mem_area *ma, const void *start, size_t len)
+{
+	const void *end = RTE_PTR_ADD(start, len);
+	const void *ma_start = ma->addr;
+	const void *ma_end = RTE_PTR_ADD(ma->addr, ma->len);
+
+	/* start overlap? */
+	if (start >= ma_start && start < ma_end)
+		return 1;
+	/* end overlap? */
+	if (end >= ma_start && end < ma_end)
+		return 1;
+	return 0;
+}
+
 static int
 find_next_n(const struct rte_fbarray *arr, unsigned int start, unsigned int n,
 	    bool used)
@@ -231,7 +264,7 @@ find_next_n(const struct rte_fbarray *arr, unsigned int start, unsigned int n,
 		return MASK_GET_IDX(msk_idx, run_start);
 	}
 	/* we didn't find anything */
-	rte_errno = used ? -ENOENT : -ENOSPC;
+	rte_errno = used ? ENOENT : ENOSPC;
 	return -1;
 }
 
@@ -287,7 +320,7 @@ find_next(const struct rte_fbarray *arr, unsigned int start, bool used)
 		return MASK_GET_IDX(idx, found);
 	}
 	/* we didn't find anything */
-	rte_errno = used ? -ENOENT : -ENOSPC;
+	rte_errno = used ? ENOENT : ENOSPC;
 	return -1;
 }
 
@@ -352,6 +385,277 @@ find_contig(const struct rte_fbarray *arr, unsigned int start, bool used)
 	return result;
 }
 
+static int
+find_prev_n(const struct rte_fbarray *arr, unsigned int start, unsigned int n,
+		bool used)
+{
+	const struct used_mask *msk = get_used_mask(arr->data, arr->elt_sz,
+			arr->len);
+	unsigned int msk_idx, lookbehind_idx, first, first_mod;
+	uint64_t ignore_msk;
+
+	/*
+	 * mask only has granularity of MASK_ALIGN, but start may not be aligned
+	 * on that boundary, so construct a special mask to exclude anything we
+	 * don't want to see to avoid confusing ctz.
+	 */
+	first = MASK_LEN_TO_IDX(start);
+	first_mod = MASK_LEN_TO_MOD(start);
+	/* we're going backwards, so mask must start from the top */
+	ignore_msk = first_mod == MASK_ALIGN - 1 ?
+				-1ULL : /* prevent overflow */
+				~(-1ULL << (first_mod + 1));
+
+	/* go backwards, include zero */
+	msk_idx = first;
+	do {
+		uint64_t cur_msk, lookbehind_msk;
+		unsigned int run_start, run_end, ctz, left;
+		bool found = false;
+		/*
+		 * The process of getting n consecutive bits from the top for
+		 * arbitrary n is a bit involved, but here it is in a nutshell:
+		 *
+		 *  1. let n be the number of consecutive bits we're looking for
+		 *  2. check if n can fit in one mask, and if so, do n-1
+		 *     lshift-ands to see if there is an appropriate run inside
+		 *     our current mask
+		 *    2a. if we found a run, bail out early
+		 *    2b. if we didn't find a run, proceed
+		 *  3. invert the mask and count trailing zeroes (that is, count
+		 *     how many consecutive set bits we had starting from the
+		 *     start of current mask) as k
+		 *    3a. if k is 0, continue to next mask
+		 *    3b. if k is not 0, we have a potential run
+		 *  4. to satisfy our requirements, next mask must have n-k
+		 *     consecutive set bits at the end, so we will do (n-k-1)
+		 *     lshift-ands and check if last bit is set.
+		 *
+		 * Step 4 will need to be repeated if (n-k) > MASK_ALIGN until
+		 * we either run out of masks, lose the run, or find what we
+		 * were looking for.
+		 */
+		cur_msk = msk->data[msk_idx];
+		left = n;
+
+		/* if we're looking for free spaces, invert the mask */
+		if (!used)
+			cur_msk = ~cur_msk;
+
+		/* if we have an ignore mask, ignore once */
+		if (ignore_msk) {
+			cur_msk &= ignore_msk;
+			ignore_msk = 0;
+		}
+
+		/* if n can fit in within a single mask, do a search */
+		if (n <= MASK_ALIGN) {
+			uint64_t tmp_msk = cur_msk;
+			unsigned int s_idx;
+			for (s_idx = 0; s_idx < n - 1; s_idx++)
+				tmp_msk &= tmp_msk << 1ULL;
+			/* we found what we were looking for */
+			if (tmp_msk != 0) {
+				/* clz will give us offset from end of mask, and
+				 * we only get the end of our run, not start,
+				 * so adjust result to point to where start
+				 * would have been.
+				 */
+				run_start = MASK_ALIGN -
+						__builtin_clzll(tmp_msk) - n;
+				return MASK_GET_IDX(msk_idx, run_start);
+			}
+		}
+
+		/*
+		 * we didn't find our run within the mask, or n > MASK_ALIGN,
+		 * so we're going for plan B.
+		 */
+
+		/* count trailing zeroes on inverted mask */
+		if (~cur_msk == 0)
+			ctz = sizeof(cur_msk) * 8;
+		else
+			ctz = __builtin_ctzll(~cur_msk);
+
+		/* if there aren't any runs at the start either, just
+		 * continue
+		 */
+		if (ctz == 0)
+			continue;
+
+		/* we have a partial run at the start, so try looking behind */
+		run_end = MASK_GET_IDX(msk_idx, ctz);
+		left -= ctz;
+
+		/* go backwards, include zero */
+		lookbehind_idx = msk_idx - 1;
+
+		/* we can't lookbehind as we've run out of masks, so stop */
+		if (msk_idx == 0)
+			break;
+
+		do {
+			const uint64_t last_bit = 1ULL << (MASK_ALIGN - 1);
+			unsigned int s_idx, need;
+
+			lookbehind_msk = msk->data[lookbehind_idx];
+
+			/* if we're looking for free space, invert the mask */
+			if (!used)
+				lookbehind_msk = ~lookbehind_msk;
+
+			/* figure out how many consecutive bits we need here */
+			need = RTE_MIN(left, MASK_ALIGN);
+
+			for (s_idx = 0; s_idx < need - 1; s_idx++)
+				lookbehind_msk &= lookbehind_msk << 1ULL;
+
+			/* if last bit is not set, we've lost the run */
+			if ((lookbehind_msk & last_bit) == 0) {
+				/*
+				 * we've scanned this far, so we know there are
+				 * no runs in the space we've lookbehind-scanned
+				 * as well, so skip that on next iteration.
+				 */
+				ignore_msk = -1ULL << need;
+				msk_idx = lookbehind_idx;
+				break;
+			}
+
+			left -= need;
+
+			/* check if we've found what we were looking for */
+			if (left == 0) {
+				found = true;
+				break;
+			}
+		} while ((lookbehind_idx--) != 0); /* decrement after check to
+						    * include zero
+						    */
+
+		/* we didn't find anything, so continue */
+		if (!found)
+			continue;
+
+		/* we've found what we were looking for, but we only know where
+		 * the run ended, so calculate start position.
+		 */
+		return run_end - n;
+	} while (msk_idx-- != 0); /* decrement after check to include zero */
+	/* we didn't find anything */
+	rte_errno = used ? ENOENT : ENOSPC;
+	return -1;
+}
+
+static int
+find_prev(const struct rte_fbarray *arr, unsigned int start, bool used)
+{
+	const struct used_mask *msk = get_used_mask(arr->data, arr->elt_sz,
+			arr->len);
+	unsigned int idx, first, first_mod;
+	uint64_t ignore_msk;
+
+	/*
+	 * mask only has granularity of MASK_ALIGN, but start may not be aligned
+	 * on that boundary, so construct a special mask to exclude anything we
+	 * don't want to see to avoid confusing clz.
+	 */
+	first = MASK_LEN_TO_IDX(start);
+	first_mod = MASK_LEN_TO_MOD(start);
+	/* we're going backwards, so mask must start from the top */
+	ignore_msk = first_mod == MASK_ALIGN - 1 ?
+				-1ULL : /* prevent overflow */
+				~(-1ULL << (first_mod + 1));
+
+	/* go backwards, include zero */
+	idx = first;
+	do {
+		uint64_t cur = msk->data[idx];
+		int found;
+
+		/* if we're looking for free entries, invert mask */
+		if (!used)
+			cur = ~cur;
+
+		/* ignore everything before start on first iteration */
+		if (idx == first)
+			cur &= ignore_msk;
+
+		/* check if we have any entries */
+		if (cur == 0)
+			continue;
+
+		/*
+		 * find last set bit - that will correspond to whatever it is
+		 * that we're looking for. we're counting trailing zeroes, thus
+		 * the value we get is counted from end of mask, so calculate
+		 * position from start of mask.
+		 */
+		found = MASK_ALIGN - __builtin_clzll(cur) - 1;
+
+		return MASK_GET_IDX(idx, found);
+	} while (idx-- != 0); /* decrement after check  to include zero*/
+
+	/* we didn't find anything */
+	rte_errno = used ? ENOENT : ENOSPC;
+	return -1;
+}
+
+static int
+find_rev_contig(const struct rte_fbarray *arr, unsigned int start, bool used)
+{
+	const struct used_mask *msk = get_used_mask(arr->data, arr->elt_sz,
+			arr->len);
+	unsigned int idx, first, first_mod;
+	unsigned int need_len, result = 0;
+
+	first = MASK_LEN_TO_IDX(start);
+	first_mod = MASK_LEN_TO_MOD(start);
+
+	/* go backwards, include zero */
+	idx = first;
+	do {
+		uint64_t cur = msk->data[idx];
+		unsigned int run_len;
+
+		need_len = MASK_ALIGN;
+
+		/* if we're looking for free entries, invert mask */
+		if (!used)
+			cur = ~cur;
+
+		/* ignore everything after start on first iteration */
+		if (idx == first) {
+			unsigned int end_len = MASK_ALIGN - first_mod - 1;
+			cur <<= end_len;
+			/* at the start, we don't need the full mask len */
+			need_len -= end_len;
+		}
+
+		/* we will be looking for zeroes, so invert the mask */
+		cur = ~cur;
+
+		/* if mask is zero, we have a complete run */
+		if (cur == 0)
+			goto endloop;
+
+		/*
+		 * see where run ends, starting from the end.
+		 */
+		run_len = __builtin_clzll(cur);
+
+		/* add however many zeroes we've had in the last run and quit */
+		if (run_len < need_len) {
+			result += run_len;
+			break;
+		}
+endloop:
+		result += need_len;
+	} while (idx-- != 0); /* decrement after check to include zero */
+	return result;
+}
+
 static int
 set_used(struct rte_fbarray *arr, unsigned int idx, bool used)
 {
@@ -405,13 +709,14 @@ fully_validate(const char *name, unsigned int elt_sz, unsigned int len)
 	return 0;
 }
 
-int __rte_experimental
+int
 rte_fbarray_init(struct rte_fbarray *arr, const char *name, unsigned int len,
 		unsigned int elt_sz)
 {
 	size_t page_sz, mmap_len;
 	char path[PATH_MAX];
 	struct used_mask *msk;
+	struct mem_area *ma = NULL;
 	void *data = NULL;
 	int fd = -1;
 
@@ -423,50 +728,81 @@ rte_fbarray_init(struct rte_fbarray *arr, const char *name, unsigned int len,
 	if (fully_validate(name, elt_sz, len))
 		return -1;
 
+	/* allocate mem area before doing anything */
+	ma = malloc(sizeof(*ma));
+	if (ma == NULL) {
+		rte_errno = ENOMEM;
+		return -1;
+	}
+
 	page_sz = sysconf(_SC_PAGESIZE);
-	if (page_sz == (size_t)-1)
-		goto fail;
+	if (page_sz == (size_t)-1) {
+		free(ma);
+		return -1;
+	}
 
 	/* calculate our memory limits */
 	mmap_len = calc_data_size(page_sz, elt_sz, len);
 
 	data = eal_get_virtual_area(NULL, &mmap_len, page_sz, 0, 0);
-	if (data == NULL)
-		goto fail;
+	if (data == NULL) {
+		free(ma);
+		return -1;
+	}
 
-	eal_get_fbarray_path(path, sizeof(path), name);
+	rte_spinlock_lock(&mem_area_lock);
 
-	/*
-	 * Each fbarray is unique to process namespace, i.e. the filename
-	 * depends on process prefix. Try to take out a lock and see if we
-	 * succeed. If we don't, someone else is using it already.
-	 */
-	fd = open(path, O_CREAT | O_RDWR, 0600);
-	if (fd < 0) {
-		RTE_LOG(DEBUG, EAL, "%s(): couldn't open %s: %s\n", __func__,
-				path, strerror(errno));
-		rte_errno = errno;
-		goto fail;
-	} else if (flock(fd, LOCK_EX | LOCK_NB)) {
-		RTE_LOG(DEBUG, EAL, "%s(): couldn't lock %s: %s\n", __func__,
-				path, strerror(errno));
-		rte_errno = EBUSY;
-		goto fail;
-	}
+	fd = -1;
 
-	/* take out a non-exclusive lock, so that other processes could still
-	 * attach to it, but no other process could reinitialize it.
-	 */
-	if (flock(fd, LOCK_SH | LOCK_NB)) {
-		rte_errno = errno;
-		goto fail;
-	}
+	if (internal_config.no_shconf) {
+		/* remap virtual area as writable */
+		void *new_data = mmap(data, mmap_len, PROT_READ | PROT_WRITE,
+				MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, fd, 0);
+		if (new_data == MAP_FAILED) {
+			RTE_LOG(DEBUG, EAL, "%s(): couldn't remap anonymous memory: %s\n",
+					__func__, strerror(errno));
+			goto fail;
+		}
+	} else {
+		eal_get_fbarray_path(path, sizeof(path), name);
 
-	if (resize_and_map(fd, data, mmap_len))
-		goto fail;
+		/*
+		 * Each fbarray is unique to process namespace, i.e. the
+		 * filename depends on process prefix. Try to take out a lock
+		 * and see if we succeed. If we don't, someone else is using it
+		 * already.
+		 */
+		fd = open(path, O_CREAT | O_RDWR, 0600);
+		if (fd < 0) {
+			RTE_LOG(DEBUG, EAL, "%s(): couldn't open %s: %s\n",
+					__func__, path, strerror(errno));
+			rte_errno = errno;
+			goto fail;
+		} else if (flock(fd, LOCK_EX | LOCK_NB)) {
+			RTE_LOG(DEBUG, EAL, "%s(): couldn't lock %s: %s\n",
+					__func__, path, strerror(errno));
+			rte_errno = EBUSY;
+			goto fail;
+		}
 
-	/* we've mmap'ed the file, we can now close the fd */
-	close(fd);
+		/* take out a non-exclusive lock, so that other processes could
+		 * still attach to it, but no other process could reinitialize
+		 * it.
+		 */
+		if (flock(fd, LOCK_SH | LOCK_NB)) {
+			rte_errno = errno;
+			goto fail;
+		}
+
+		if (resize_and_map(fd, data, mmap_len))
+			goto fail;
+	}
+	ma->addr = data;
+	ma->len = mmap_len;
+	ma->fd = fd;
+
+	/* do not close fd - keep it until detach/destroy */
+	TAILQ_INSERT_TAIL(&mem_area_tailq, ma, next);
 
 	/* initialize the data */
 	memset(data, 0, mmap_len);
@@ -483,18 +819,24 @@ rte_fbarray_init(struct rte_fbarray *arr, const char *name, unsigned int len,
 
 	rte_rwlock_init(&arr->rwlock);
 
+	rte_spinlock_unlock(&mem_area_lock);
+
 	return 0;
 fail:
 	if (data)
 		munmap(data, mmap_len);
 	if (fd >= 0)
 		close(fd);
+	free(ma);
+
+	rte_spinlock_unlock(&mem_area_lock);
 	return -1;
 }
 
-int __rte_experimental
+int
 rte_fbarray_attach(struct rte_fbarray *arr)
 {
+	struct mem_area *ma = NULL, *tmp = NULL;
 	size_t page_sz, mmap_len;
 	char path[PATH_MAX];
 	void *data = NULL;
@@ -514,12 +856,32 @@ rte_fbarray_attach(struct rte_fbarray *arr)
 	if (fully_validate(arr->name, arr->elt_sz, arr->len))
 		return -1;
 
+	ma = malloc(sizeof(*ma));
+	if (ma == NULL) {
+		rte_errno = ENOMEM;
+		return -1;
+	}
+
 	page_sz = sysconf(_SC_PAGESIZE);
-	if (page_sz == (size_t)-1)
-		goto fail;
+	if (page_sz == (size_t)-1) {
+		free(ma);
+		return -1;
+	}
 
 	mmap_len = calc_data_size(page_sz, arr->elt_sz, arr->len);
 
+	/* check the tailq - maybe user has already mapped this address space */
+	rte_spinlock_lock(&mem_area_lock);
+
+	TAILQ_FOREACH(tmp, &mem_area_tailq, next) {
+		if (overlap(tmp, arr->data, mmap_len)) {
+			rte_errno = EEXIST;
+			goto fail;
+		}
+	}
+
+	/* we know this memory area is unique, so proceed */
+
 	data = eal_get_virtual_area(arr->data, &mmap_len, page_sz, 0, 0);
 	if (data == NULL)
 		goto fail;
@@ -541,22 +903,34 @@ rte_fbarray_attach(struct rte_fbarray *arr)
 	if (resize_and_map(fd, data, mmap_len))
 		goto fail;
 
-	close(fd);
+	/* store our new memory area */
+	ma->addr = data;
+	ma->fd = fd; /* keep fd until detach/destroy */
+	ma->len = mmap_len;
+
+	TAILQ_INSERT_TAIL(&mem_area_tailq, ma, next);
 
 	/* we're done */
 
+	rte_spinlock_unlock(&mem_area_lock);
 	return 0;
 fail:
 	if (data)
 		munmap(data, mmap_len);
 	if (fd >= 0)
 		close(fd);
+	free(ma);
+	rte_spinlock_unlock(&mem_area_lock);
 	return -1;
 }
 
-int __rte_experimental
+int
 rte_fbarray_detach(struct rte_fbarray *arr)
 {
+	struct mem_area *tmp = NULL;
+	size_t mmap_len;
+	int ret = -1;
+
 	if (arr == NULL) {
 		rte_errno = EINVAL;
 		return -1;
@@ -572,49 +946,121 @@ rte_fbarray_detach(struct rte_fbarray *arr)
 
 	size_t page_sz = sysconf(_SC_PAGESIZE);
 
-	/* this may already be unmapped (e.g. repeated call from previously
-	 * failed destroy(), but this is on user, we can't (easily) know if this
-	 * is still mapped.
-	 */
-	munmap(arr->data, calc_data_size(page_sz, arr->elt_sz, arr->len));
+	if (page_sz == (size_t)-1)
+		return -1;
 
-	return 0;
+	mmap_len = calc_data_size(page_sz, arr->elt_sz, arr->len);
+
+	/* does this area exist? */
+	rte_spinlock_lock(&mem_area_lock);
+
+	TAILQ_FOREACH(tmp, &mem_area_tailq, next) {
+		if (tmp->addr == arr->data && tmp->len == mmap_len)
+			break;
+	}
+	if (tmp == NULL) {
+		rte_errno = ENOENT;
+		ret = -1;
+		goto out;
+	}
+
+	munmap(arr->data, mmap_len);
+
+	/* area is unmapped, close fd and remove the tailq entry */
+	if (tmp->fd >= 0)
+		close(tmp->fd);
+	TAILQ_REMOVE(&mem_area_tailq, tmp, next);
+	free(tmp);
+
+	ret = 0;
+out:
+	rte_spinlock_unlock(&mem_area_lock);
+	return ret;
 }
 
-int __rte_experimental
+int
 rte_fbarray_destroy(struct rte_fbarray *arr)
 {
+	struct mem_area *tmp = NULL;
+	size_t mmap_len;
 	int fd, ret;
 	char path[PATH_MAX];
 
-	ret = rte_fbarray_detach(arr);
-	if (ret)
-		return ret;
+	if (arr == NULL) {
+		rte_errno = EINVAL;
+		return -1;
+	}
 
-	/* try deleting the file */
-	eal_get_fbarray_path(path, sizeof(path), arr->name);
+	/*
+	 * we don't need to synchronize detach as two values we need (element
+	 * size and total capacity) are constant for the duration of life of
+	 * the array, so the parts we care about will not race. if the user is
+	 * detaching while doing something else in the same process, we can't
+	 * really do anything about it, things will blow up either way.
+	 */
 
-	fd = open(path, O_RDONLY);
-	if (fd < 0) {
-		RTE_LOG(ERR, EAL, "Could not open fbarray file: %s\n",
-			strerror(errno));
+	size_t page_sz = sysconf(_SC_PAGESIZE);
+
+	if (page_sz == (size_t)-1)
 		return -1;
+
+	mmap_len = calc_data_size(page_sz, arr->elt_sz, arr->len);
+
+	/* does this area exist? */
+	rte_spinlock_lock(&mem_area_lock);
+
+	TAILQ_FOREACH(tmp, &mem_area_tailq, next) {
+		if (tmp->addr == arr->data && tmp->len == mmap_len)
+			break;
 	}
-	if (flock(fd, LOCK_EX | LOCK_NB)) {
-		RTE_LOG(DEBUG, EAL, "Cannot destroy fbarray - another process is using it\n");
-		rte_errno = EBUSY;
+	if (tmp == NULL) {
+		rte_errno = ENOENT;
 		ret = -1;
-	} else {
-		ret = 0;
-		unlink(path);
-		memset(arr, 0, sizeof(*arr));
+		goto out;
 	}
-	close(fd);
+	/* with no shconf, there were never any files to begin with */
+	if (!internal_config.no_shconf) {
+		/*
+		 * attempt to get an exclusive lock on the file, to ensure it
+		 * has been detached by all other processes
+		 */
+		fd = tmp->fd;
+		if (flock(fd, LOCK_EX | LOCK_NB)) {
+			RTE_LOG(DEBUG, EAL, "Cannot destroy fbarray - another process is using it\n");
+			rte_errno = EBUSY;
+			ret = -1;
+			goto out;
+		}
+
+		/* we're OK to destroy the file */
+		eal_get_fbarray_path(path, sizeof(path), arr->name);
+		if (unlink(path)) {
+			RTE_LOG(DEBUG, EAL, "Cannot unlink fbarray: %s\n",
+				strerror(errno));
+			rte_errno = errno;
+			/*
+			 * we're still holding an exclusive lock, so drop it to
+			 * shared.
+			 */
+			flock(fd, LOCK_SH | LOCK_NB);
+
+			ret = -1;
+			goto out;
+		}
+		close(fd);
+	}
+	munmap(arr->data, mmap_len);
 
+	/* area is unmapped, remove the tailq entry */
+	TAILQ_REMOVE(&mem_area_tailq, tmp, next);
+	free(tmp);
+	ret = 0;
+out:
+	rte_spinlock_unlock(&mem_area_lock);
 	return ret;
 }
 
-void * __rte_experimental
+void *
 rte_fbarray_get(const struct rte_fbarray *arr, unsigned int idx)
 {
 	void *ret = NULL;
@@ -633,19 +1079,19 @@ rte_fbarray_get(const struct rte_fbarray *arr, unsigned int idx)
 	return ret;
 }
 
-int __rte_experimental
+int
 rte_fbarray_set_used(struct rte_fbarray *arr, unsigned int idx)
 {
 	return set_used(arr, idx, true);
 }
 
-int __rte_experimental
+int
 rte_fbarray_set_free(struct rte_fbarray *arr, unsigned int idx)
 {
 	return set_used(arr, idx, false);
 }
 
-int __rte_experimental
+int
 rte_fbarray_is_used(struct rte_fbarray *arr, unsigned int idx)
 {
 	struct used_mask *msk;
@@ -672,8 +1118,8 @@ rte_fbarray_is_used(struct rte_fbarray *arr, unsigned int idx)
 	return ret;
 }
 
-int __rte_experimental
-rte_fbarray_find_next_free(struct rte_fbarray *arr, unsigned int start)
+static int
+fbarray_find(struct rte_fbarray *arr, unsigned int start, bool next, bool used)
 {
 	int ret = -1;
 
@@ -685,73 +1131,146 @@ rte_fbarray_find_next_free(struct rte_fbarray *arr, unsigned int start)
 	/* prevent array from changing under us */
 	rte_rwlock_read_lock(&arr->rwlock);
 
-	if (arr->len == arr->count) {
-		rte_errno = ENOSPC;
-		goto out;
+	/* cheap checks to prevent doing useless work */
+	if (!used) {
+		if (arr->len == arr->count) {
+			rte_errno = ENOSPC;
+			goto out;
+		}
+		if (arr->count == 0) {
+			ret = start;
+			goto out;
+		}
+	} else {
+		if (arr->count == 0) {
+			rte_errno = ENOENT;
+			goto out;
+		}
+		if (arr->len == arr->count) {
+			ret = start;
+			goto out;
+		}
 	}
-
-	ret = find_next(arr, start, false);
+	if (next)
+		ret = find_next(arr, start, used);
+	else
+		ret = find_prev(arr, start, used);
 out:
 	rte_rwlock_read_unlock(&arr->rwlock);
 	return ret;
 }
 
-int __rte_experimental
+int
+rte_fbarray_find_next_free(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find(arr, start, true, false);
+}
+
+int
 rte_fbarray_find_next_used(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find(arr, start, true, true);
+}
+
+int
+rte_fbarray_find_prev_free(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find(arr, start, false, false);
+}
+
+int
+rte_fbarray_find_prev_used(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find(arr, start, false, true);
+}
+
+static int
+fbarray_find_n(struct rte_fbarray *arr, unsigned int start, unsigned int n,
+		bool next, bool used)
 {
 	int ret = -1;
 
-	if (arr == NULL || start >= arr->len) {
+	if (arr == NULL || start >= arr->len || n > arr->len || n == 0) {
 		rte_errno = EINVAL;
 		return -1;
 	}
+	if (next && (arr->len - start) < n) {
+		rte_errno = used ? ENOENT : ENOSPC;
+		return -1;
+	}
+	if (!next && start < (n - 1)) {
+		rte_errno = used ? ENOENT : ENOSPC;
+		return -1;
+	}
 
 	/* prevent array from changing under us */
 	rte_rwlock_read_lock(&arr->rwlock);
 
-	if (arr->count == 0) {
-		rte_errno = ENOENT;
-		goto out;
+	/* cheap checks to prevent doing useless work */
+	if (!used) {
+		if (arr->len == arr->count || arr->len - arr->count < n) {
+			rte_errno = ENOSPC;
+			goto out;
+		}
+		if (arr->count == 0) {
+			ret = next ? start : start - n + 1;
+			goto out;
+		}
+	} else {
+		if (arr->count < n) {
+			rte_errno = ENOENT;
+			goto out;
+		}
+		if (arr->count == arr->len) {
+			ret = next ? start : start - n + 1;
+			goto out;
+		}
 	}
 
-	ret = find_next(arr, start, true);
+	if (next)
+		ret = find_next_n(arr, start, n, used);
+	else
+		ret = find_prev_n(arr, start, n, used);
 out:
 	rte_rwlock_read_unlock(&arr->rwlock);
 	return ret;
 }
 
-int __rte_experimental
+int
 rte_fbarray_find_next_n_free(struct rte_fbarray *arr, unsigned int start,
 		unsigned int n)
 {
-	int ret = -1;
-
-	if (arr == NULL || start >= arr->len || n > arr->len) {
-		rte_errno = EINVAL;
-		return -1;
-	}
-
-	/* prevent array from changing under us */
-	rte_rwlock_read_lock(&arr->rwlock);
+	return fbarray_find_n(arr, start, n, true, false);
+}
 
-	if (arr->len == arr->count || arr->len - arr->count < n) {
-		rte_errno = ENOSPC;
-		goto out;
-	}
+int
+rte_fbarray_find_next_n_used(struct rte_fbarray *arr, unsigned int start,
+		unsigned int n)
+{
+	return fbarray_find_n(arr, start, n, true, true);
+}
 
-	ret = find_next_n(arr, start, n, false);
-out:
-	rte_rwlock_read_unlock(&arr->rwlock);
-	return ret;
+int
+rte_fbarray_find_prev_n_free(struct rte_fbarray *arr, unsigned int start,
+		unsigned int n)
+{
+	return fbarray_find_n(arr, start, n, false, false);
 }
 
-int __rte_experimental
-rte_fbarray_find_next_n_used(struct rte_fbarray *arr, unsigned int start,
+int
+rte_fbarray_find_prev_n_used(struct rte_fbarray *arr, unsigned int start,
 		unsigned int n)
+{
+	return fbarray_find_n(arr, start, n, false, true);
+}
+
+static int
+fbarray_find_contig(struct rte_fbarray *arr, unsigned int start, bool next,
+		bool used)
 {
 	int ret = -1;
 
-	if (arr == NULL || start >= arr->len || n > arr->len) {
+	if (arr == NULL || start >= arr->len) {
 		rte_errno = EINVAL;
 		return -1;
 	}
@@ -759,66 +1278,178 @@ rte_fbarray_find_next_n_used(struct rte_fbarray *arr, unsigned int start,
 	/* prevent array from changing under us */
 	rte_rwlock_read_lock(&arr->rwlock);
 
-	if (arr->count < n) {
-		rte_errno = ENOENT;
-		goto out;
+	/* cheap checks to prevent doing useless work */
+	if (used) {
+		if (arr->count == 0) {
+			ret = 0;
+			goto out;
+		}
+		if (next && arr->count == arr->len) {
+			ret = arr->len - start;
+			goto out;
+		}
+		if (!next && arr->count == arr->len) {
+			ret = start + 1;
+			goto out;
+		}
+	} else {
+		if (arr->len == arr->count) {
+			ret = 0;
+			goto out;
+		}
+		if (next && arr->count == 0) {
+			ret = arr->len - start;
+			goto out;
+		}
+		if (!next && arr->count == 0) {
+			ret = start + 1;
+			goto out;
+		}
 	}
 
-	ret = find_next_n(arr, start, n, true);
+	if (next)
+		ret = find_contig(arr, start, used);
+	else
+		ret = find_rev_contig(arr, start, used);
 out:
 	rte_rwlock_read_unlock(&arr->rwlock);
 	return ret;
 }
 
-int __rte_experimental
-rte_fbarray_find_contig_free(struct rte_fbarray *arr, unsigned int start)
+static int
+fbarray_find_biggest(struct rte_fbarray *arr, unsigned int start, bool used,
+		bool rev)
 {
-	int ret = -1;
+	int cur_idx, next_idx, cur_len, biggest_idx, biggest_len;
+	/* don't stack if conditions, use function pointers instead */
+	int (*find_func)(struct rte_fbarray *, unsigned int);
+	int (*find_contig_func)(struct rte_fbarray *, unsigned int);
 
 	if (arr == NULL || start >= arr->len) {
 		rte_errno = EINVAL;
 		return -1;
 	}
+	/* the other API calls already do their fair share of cheap checks, so
+	 * no need to do them here.
+	 */
 
-	/* prevent array from changing under us */
+	/* the API's called are thread-safe, but something may still happen
+	 * inbetween the API calls, so lock the fbarray. all other API's are
+	 * read-locking the fbarray, so read lock here is OK.
+	 */
 	rte_rwlock_read_lock(&arr->rwlock);
 
-	if (arr->len == arr->count) {
-		rte_errno = ENOSPC;
-		goto out;
+	/* pick out appropriate functions */
+	if (used) {
+		if (rev) {
+			find_func = rte_fbarray_find_prev_used;
+			find_contig_func = rte_fbarray_find_rev_contig_used;
+		} else {
+			find_func = rte_fbarray_find_next_used;
+			find_contig_func = rte_fbarray_find_contig_used;
+		}
+	} else {
+		if (rev) {
+			find_func = rte_fbarray_find_prev_free;
+			find_contig_func = rte_fbarray_find_rev_contig_free;
+		} else {
+			find_func = rte_fbarray_find_next_free;
+			find_contig_func = rte_fbarray_find_contig_free;
+		}
 	}
 
-	if (arr->count == 0) {
-		ret = arr->len - start;
-		goto out;
+	cur_idx = start;
+	biggest_idx = -1; /* default is error */
+	biggest_len = 0;
+	for (;;) {
+		cur_idx = find_func(arr, cur_idx);
+
+		/* block found, check its length */
+		if (cur_idx >= 0) {
+			cur_len = find_contig_func(arr, cur_idx);
+			/* decide where we go next */
+			next_idx = rev ? cur_idx - cur_len : cur_idx + cur_len;
+			/* move current index to start of chunk */
+			cur_idx = rev ? next_idx + 1 : cur_idx;
+
+			if (cur_len > biggest_len) {
+				biggest_idx = cur_idx;
+				biggest_len = cur_len;
+			}
+			cur_idx = next_idx;
+			/* in reverse mode, next_idx may be -1 if chunk started
+			 * at array beginning. this means there's no more work
+			 * to do.
+			 */
+			if (cur_idx < 0)
+				break;
+		} else {
+			/* nothing more to find, stop. however, a failed API
+			 * call has set rte_errno, which we want to ignore, as
+			 * reaching the end of fbarray is not an error.
+			 */
+			rte_errno = 0;
+			break;
+		}
 	}
+	/* if we didn't find anything at all, set rte_errno */
+	if (biggest_idx < 0)
+		rte_errno = used ? ENOENT : ENOSPC;
 
-	ret = find_contig(arr, start, false);
-out:
 	rte_rwlock_read_unlock(&arr->rwlock);
-	return ret;
+	return biggest_idx;
 }
 
-int __rte_experimental
-rte_fbarray_find_contig_used(struct rte_fbarray *arr, unsigned int start)
+int
+rte_fbarray_find_biggest_free(struct rte_fbarray *arr, unsigned int start)
 {
-	int ret = -1;
+	return fbarray_find_biggest(arr, start, false, false);
+}
 
-	if (arr == NULL || start >= arr->len) {
-		rte_errno = EINVAL;
-		return -1;
-	}
+int
+rte_fbarray_find_biggest_used(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_biggest(arr, start, true, false);
+}
 
-	/* prevent array from changing under us */
-	rte_rwlock_read_lock(&arr->rwlock);
+int
+rte_fbarray_find_rev_biggest_free(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_biggest(arr, start, false, true);
+}
+
+int
+rte_fbarray_find_rev_biggest_used(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_biggest(arr, start, true, true);
+}
 
-	ret = find_contig(arr, start, true);
 
-	rte_rwlock_read_unlock(&arr->rwlock);
-	return ret;
+int
+rte_fbarray_find_contig_free(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_contig(arr, start, true, false);
+}
+
+int
+rte_fbarray_find_contig_used(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_contig(arr, start, true, true);
+}
+
+int
+rte_fbarray_find_rev_contig_free(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_contig(arr, start, false, false);
+}
+
+int
+rte_fbarray_find_rev_contig_used(struct rte_fbarray *arr, unsigned int start)
+{
+	return fbarray_find_contig(arr, start, false, true);
 }
 
-int __rte_experimental
+int
 rte_fbarray_find_idx(const struct rte_fbarray *arr, const void *elt)
 {
 	void *end;
@@ -844,7 +1475,7 @@ rte_fbarray_find_idx(const struct rte_fbarray *arr, const void *elt)
 	return ret;
 }
 
-void __rte_experimental
+void
 rte_fbarray_dump_metadata(struct rte_fbarray *arr, FILE *f)
 {
 	struct used_mask *msk;