drivers/net/mlx4/mcg.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2006, 2007 Cisco Systems, Inc.  All rights reserved.
  *
  * This software is available to you under a choice of one of two
  * licenses.  You may choose to be licensed under the terms of the GNU
  * General Public License (GPL) Version 2, available from the file
  * COPYING in the main directory of this source tree, or the
  * OpenIB.org BSD license below:
  *
  *     Redistribution and use in source and binary forms, with or
  *     without modification, are permitted provided that the following
  *     conditions are met:
  *
  *      - Redistributions of source code must retain the above
  *        copyright notice, this list of conditions and the following
  *        disclaimer.
  *
  *      - Redistributions in binary form must reproduce the above
  *        copyright notice, this list of conditions and the following
  *        disclaimer in the documentation and/or other materials
  *        provided with the distribution.
  *
  * 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 <linux/init.h>
 #include <linux/string.h>
 #include <linux/slab.h>

 #include <linux/mlx4/cmd.h>

 #include "mlx4.h"

 struct mlx4_mgm {
 	__be32			next_gid_index;
 	__be32			members_count;
 	u32			reserved[2];
 	u8			gid[16];
 	__be32			qp[MLX4_QP_PER_MGM];
 };

 static const u8 zero_gid[16];	/* automatically initialized to 0 */

 static int mlx4_READ_MCG(struct mlx4_dev *dev, int index,
 			 struct mlx4_cmd_mailbox *mailbox)
 {
 	return mlx4_cmd_box(dev, 0, mailbox->dma, index, 0, MLX4_CMD_READ_MCG,
 			    MLX4_CMD_TIME_CLASS_A);
 }

 static int mlx4_WRITE_MCG(struct mlx4_dev *dev, int index,
 			  struct mlx4_cmd_mailbox *mailbox)
 {
 	return mlx4_cmd(dev, mailbox->dma, index, 0, MLX4_CMD_WRITE_MCG,
 			MLX4_CMD_TIME_CLASS_A);
 }

 static int mlx4_MGID_HASH(struct mlx4_dev *dev, struct mlx4_cmd_mailbox *mailbox,
 			  u16 *hash)
 {
 	u64 imm;
 	int err;

 	err = mlx4_cmd_imm(dev, mailbox->dma, &imm, 0, 0, MLX4_CMD_MGID_HASH,
 			   MLX4_CMD_TIME_CLASS_A);

 	if (!err)
 		*hash = imm;

 	return err;
 }

 /*
  * Caller must hold MCG table semaphore.  gid and mgm parameters must
  * be properly aligned for command interface.
  *
  *  Returns 0 unless a firmware command error occurs.
  *
  * If GID is found in MGM or MGM is empty, *index = *hash, *prev = -1
  * and *mgm holds MGM entry.
  *
  * if GID is found in AMGM, *index = index in AMGM, *prev = index of
  * previous entry in hash chain and *mgm holds AMGM entry.
  *
  * If no AMGM exists for given gid, *index = -1, *prev = index of last
  * entry in hash chain and *mgm holds end of hash chain.
  */
 static int find_mgm(struct mlx4_dev *dev,
 		    u8 *gid, struct mlx4_cmd_mailbox *mgm_mailbox,
 		    u16 *hash, int *prev, int *index)
 {
 	struct mlx4_cmd_mailbox *mailbox;
 	struct mlx4_mgm *mgm = mgm_mailbox->buf;
 	u8 *mgid;
 	int err;

 	mailbox = mlx4_alloc_cmd_mailbox(dev);
 	if (IS_ERR(mailbox))
 		return -ENOMEM;
 	mgid = mailbox->buf;

 	memcpy(mgid, gid, 16);

 	err = mlx4_MGID_HASH(dev, mailbox, hash);
 	mlx4_free_cmd_mailbox(dev, mailbox);
 	if (err)
 		return err;

 	if (0)
 		mlx4_dbg(dev, "Hash for %04x:%04x:%04x:%04x:"
 			  "%04x:%04x:%04x:%04x is %04x\n",
 			  be16_to_cpu(((__be16 *) gid)[0]),
 			  be16_to_cpu(((__be16 *) gid)[1]),
 			  be16_to_cpu(((__be16 *) gid)[2]),
 			  be16_to_cpu(((__be16 *) gid)[3]),
 			  be16_to_cpu(((__be16 *) gid)[4]),
 			  be16_to_cpu(((__be16 *) gid)[5]),
 			  be16_to_cpu(((__be16 *) gid)[6]),
 			  be16_to_cpu(((__be16 *) gid)[7]),
 			  *hash);

 	*index = *hash;
 	*prev  = -1;

 	do {
 		err = mlx4_READ_MCG(dev, *index, mgm_mailbox);
 		if (err)
 			return err;

 		if (!memcmp(mgm->gid, zero_gid, 16)) {
 			if (*index != *hash) {
 				mlx4_err(dev, "Found zero MGID in AMGM.\n");
 				err = -EINVAL;
 			}
 			return err;
 		}

 		if (!memcmp(mgm->gid, gid, 16))
 			return err;

 		*prev = *index;
 		*index = be32_to_cpu(mgm->next_gid_index) >> 6;
 	} while (*index);

 	*index = -1;
 	return err;
 }

 int mlx4_multicast_attach(struct mlx4_dev *dev, struct mlx4_qp *qp, u8 gid[16])
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
 	struct mlx4_cmd_mailbox *mailbox;
 	struct mlx4_mgm *mgm;
 	u32 members_count;
 	u16 hash;
 	int index, prev;
 	int link = 0;
 	int i;
 	int err;

 	mailbox = mlx4_alloc_cmd_mailbox(dev);
 	if (IS_ERR(mailbox))
 		return PTR_ERR(mailbox);
 	mgm = mailbox->buf;

 	mutex_lock(&priv->mcg_table.mutex);

 	err = find_mgm(dev, gid, mailbox, &hash, &prev, &index);
 	if (err)
 		goto out;

 	if (index != -1) {
 		if (!memcmp(mgm->gid, zero_gid, 16))
 			memcpy(mgm->gid, gid, 16);
 	} else {
 		link = 1;

 		index = mlx4_bitmap_alloc(&priv->mcg_table.bitmap);
 		if (index == -1) {
 			mlx4_err(dev, "No AMGM entries left\n");
 			err = -ENOMEM;
 			goto out;
 		}
 		index += dev->caps.num_mgms;

 		memset(mgm, 0, sizeof *mgm);
 		memcpy(mgm->gid, gid, 16);
 	}

 	members_count = be32_to_cpu(mgm->members_count);
 	if (members_count == MLX4_QP_PER_MGM) {
 		mlx4_err(dev, "MGM at index %x is full.\n", index);
 		err = -ENOMEM;
 		goto out;
 	}

 	for (i = 0; i < members_count; ++i)
 		if (mgm->qp[i] == cpu_to_be32(qp->qpn)) {
 			mlx4_dbg(dev, "QP %06x already a member of MGM\n", qp->qpn);
 			err = 0;
 			goto out;
 		}

 	mgm->qp[members_count++] = cpu_to_be32(qp->qpn);
 	mgm->members_count       = cpu_to_be32(members_count);

 	err = mlx4_WRITE_MCG(dev, index, mailbox);
 	if (err)
 		goto out;

 	if (!link)
 		goto out;

 	err = mlx4_READ_MCG(dev, prev, mailbox);
 	if (err)
 		goto out;

 	mgm->next_gid_index = cpu_to_be32(index << 6);

 	err = mlx4_WRITE_MCG(dev, prev, mailbox);
 	if (err)
 		goto out;

 out:
 	if (err && link && index != -1) {
 		if (index < dev->caps.num_mgms)
 			mlx4_warn(dev, "Got AMGM index %d < %d",
 				  index, dev->caps.num_mgms);
 		else
 			mlx4_bitmap_free(&priv->mcg_table.bitmap,
 					 index - dev->caps.num_mgms);
 	}
 	mutex_unlock(&priv->mcg_table.mutex);

 	mlx4_free_cmd_mailbox(dev, mailbox);
 	return err;
 }
 EXPORT_SYMBOL_GPL(mlx4_multicast_attach);

 int mlx4_multicast_detach(struct mlx4_dev *dev, struct mlx4_qp *qp, u8 gid[16])
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
 	struct mlx4_cmd_mailbox *mailbox;
 	struct mlx4_mgm *mgm;
 	u32 members_count;
 	u16 hash;
 	int prev, index;
 	int i, loc;
 	int err;

 	mailbox = mlx4_alloc_cmd_mailbox(dev);
 	if (IS_ERR(mailbox))
 		return PTR_ERR(mailbox);
 	mgm = mailbox->buf;

 	mutex_lock(&priv->mcg_table.mutex);

 	err = find_mgm(dev, gid, mailbox, &hash, &prev, &index);
 	if (err)
 		goto out;

 	if (index == -1) {
 		mlx4_err(dev, "MGID %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x "
 			  "not found\n",
 			  be16_to_cpu(((__be16 *) gid)[0]),
 			  be16_to_cpu(((__be16 *) gid)[1]),
 			  be16_to_cpu(((__be16 *) gid)[2]),
 			  be16_to_cpu(((__be16 *) gid)[3]),
 			  be16_to_cpu(((__be16 *) gid)[4]),
 			  be16_to_cpu(((__be16 *) gid)[5]),
 			  be16_to_cpu(((__be16 *) gid)[6]),
 			  be16_to_cpu(((__be16 *) gid)[7]));
 		err = -EINVAL;
 		goto out;
 	}

 	members_count = be32_to_cpu(mgm->members_count);
 	for (loc = -1, i = 0; i < members_count; ++i)
 		if (mgm->qp[i] == cpu_to_be32(qp->qpn))
 			loc = i;

 	if (loc == -1) {
 		mlx4_err(dev, "QP %06x not found in MGM\n", qp->qpn);
 		err = -EINVAL;
 		goto out;
 	}


 	mgm->members_count = cpu_to_be32(--members_count);
 	mgm->qp[loc]       = mgm->qp[i - 1];
 	mgm->qp[i - 1]     = 0;

 	if (i != 1) {
 		err = mlx4_WRITE_MCG(dev, index, mailbox);
 		goto out;
 	}

 	if (prev == -1) {
 		/* Remove entry from MGM */
 		int amgm_index = be32_to_cpu(mgm->next_gid_index) >> 6;
 		if (amgm_index) {
 			err = mlx4_READ_MCG(dev, amgm_index, mailbox);
 			if (err)
 				goto out;
 		} else
 			memset(mgm->gid, 0, 16);

 		err = mlx4_WRITE_MCG(dev, index, mailbox);
 		if (err)
 			goto out;

 		if (amgm_index) {
 			if (amgm_index < dev->caps.num_mgms)
 				mlx4_warn(dev, "MGM entry %d had AMGM index %d < %d",
 					  index, amgm_index, dev->caps.num_mgms);
 			else
 				mlx4_bitmap_free(&priv->mcg_table.bitmap,
 						 amgm_index - dev->caps.num_mgms);
 		}
 	} else {
 		/* Remove entry from AMGM */
 		int cur_next_index = be32_to_cpu(mgm->next_gid_index) >> 6;
 		err = mlx4_READ_MCG(dev, prev, mailbox);
 		if (err)
 			goto out;

 		mgm->next_gid_index = cpu_to_be32(cur_next_index << 6);

 		err = mlx4_WRITE_MCG(dev, prev, mailbox);
 		if (err)
 			goto out;

 		if (index < dev->caps.num_mgms)
 			mlx4_warn(dev, "entry %d had next AMGM index %d < %d",
 				  prev, index, dev->caps.num_mgms);
 		else
 			mlx4_bitmap_free(&priv->mcg_table.bitmap,
 					 index - dev->caps.num_mgms);
 	}

 out:
 	mutex_unlock(&priv->mcg_table.mutex);

 	mlx4_free_cmd_mailbox(dev, mailbox);
 	return err;
 }
 EXPORT_SYMBOL_GPL(mlx4_multicast_detach);

 int mlx4_init_mcg_table(struct mlx4_dev *dev)
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
 	int err;

 	err = mlx4_bitmap_init(&priv->mcg_table.bitmap,
 			       dev->caps.num_amgms, dev->caps.num_amgms - 1, 0);
 	if (err)
 		return err;

 	mutex_init(&priv->mcg_table.mutex);

 	return 0;
 }

 void mlx4_cleanup_mcg_table(struct mlx4_dev *dev)
 {
 	mlx4_bitmap_cleanup(&mlx4_priv(dev)->mcg_table.bitmap);
 }
	/*
	* Copyright (c) 2006, 2007 Cisco Systems, Inc. All rights reserved.
	*
	* This software is available to you under a choice of one of two
	* licenses. You may choose to be licensed under the terms of the GNU
	* General Public License (GPL) Version 2, available from the file
	* COPYING in the main directory of this source tree, or the
	* OpenIB.org BSD license below:
	*
	* Redistribution and use in source and binary forms, with or
	* without modification, are permitted provided that the following
	* conditions are met:
	*
	* - Redistributions of source code must retain the above
	* copyright notice, this list of conditions and the following
	* disclaimer.
	*
	* - Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following
	* disclaimer in the documentation and/or other materials
	* provided with the distribution.
	*
	* 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 <linux/init.h>
	#include <linux/string.h>
	#include <linux/slab.h>

	#include <linux/mlx4/cmd.h>

	#include "mlx4.h"

	struct mlx4_mgm {
	__be32 next_gid_index;
	__be32 members_count;
	u32 reserved[2];
	u8 gid[16];
	__be32 qp[MLX4_QP_PER_MGM];
	};

	static const u8 zero_gid[16]; /* automatically initialized to 0 */

	static int mlx4_READ_MCG(struct mlx4_dev *dev, int index,
	struct mlx4_cmd_mailbox *mailbox)
	{
	return mlx4_cmd_box(dev, 0, mailbox->dma, index, 0, MLX4_CMD_READ_MCG,
	MLX4_CMD_TIME_CLASS_A);
	}

	static int mlx4_WRITE_MCG(struct mlx4_dev *dev, int index,
	struct mlx4_cmd_mailbox *mailbox)
	{
	return mlx4_cmd(dev, mailbox->dma, index, 0, MLX4_CMD_WRITE_MCG,
	MLX4_CMD_TIME_CLASS_A);
	}

	static int mlx4_MGID_HASH(struct mlx4_dev dev, struct mlx4_cmd_mailbox mailbox,
	u16 *hash)
	{
	u64 imm;
	int err;

	err = mlx4_cmd_imm(dev, mailbox->dma, &imm, 0, 0, MLX4_CMD_MGID_HASH,
	MLX4_CMD_TIME_CLASS_A);

	if (!err)
	*hash = imm;

	return err;
	}

	/*
	* Caller must hold MCG table semaphore. gid and mgm parameters must
	* be properly aligned for command interface.
	*
	* Returns 0 unless a firmware command error occurs.
	*
	* If GID is found in MGM or MGM is empty, index = hash, *prev = -1
	* and *mgm holds MGM entry.
	*
	* if GID is found in AMGM, index = index in AMGM, prev = index of
	* previous entry in hash chain and *mgm holds AMGM entry.
	*
	* If no AMGM exists for given gid, index = -1, prev = index of last
	* entry in hash chain and *mgm holds end of hash chain.
	*/
	static int find_mgm(struct mlx4_dev *dev,
	u8 gid, struct mlx4_cmd_mailbox mgm_mailbox,
	u16 hash, int prev, int *index)
	{
	struct mlx4_cmd_mailbox *mailbox;
	struct mlx4_mgm *mgm = mgm_mailbox->buf;
	u8 *mgid;
	int err;

	mailbox = mlx4_alloc_cmd_mailbox(dev);
	if (IS_ERR(mailbox))
	return -ENOMEM;
	mgid = mailbox->buf;

	memcpy(mgid, gid, 16);

	err = mlx4_MGID_HASH(dev, mailbox, hash);
	mlx4_free_cmd_mailbox(dev, mailbox);
	if (err)
	return err;

	if (0)
	mlx4_dbg(dev, "Hash for %04x:%04x:%04x:%04x:"
	"%04x:%04x:%04x:%04x is %04x\n",
	be16_to_cpu(((__be16 *) gid)[0]),
	be16_to_cpu(((__be16 *) gid)[1]),
	be16_to_cpu(((__be16 *) gid)[2]),
	be16_to_cpu(((__be16 *) gid)[3]),
	be16_to_cpu(((__be16 *) gid)[4]),
	be16_to_cpu(((__be16 *) gid)[5]),
	be16_to_cpu(((__be16 *) gid)[6]),
	be16_to_cpu(((__be16 *) gid)[7]),
	*hash);

	index = hash;
	*prev = -1;

	do {
	err = mlx4_READ_MCG(dev, *index, mgm_mailbox);
	if (err)
	return err;

	if (!memcmp(mgm->gid, zero_gid, 16)) {
	if (index != hash) {
	mlx4_err(dev, "Found zero MGID in AMGM.\n");
	err = -EINVAL;
	}
	return err;
	}

	if (!memcmp(mgm->gid, gid, 16))
	return err;

	prev = index;
	*index = be32_to_cpu(mgm->next_gid_index) >> 6;
	} while (*index);

	*index = -1;
	return err;
	}

	int mlx4_multicast_attach(struct mlx4_dev dev, struct mlx4_qp qp, u8 gid[16])
	{
	struct mlx4_priv *priv = mlx4_priv(dev);
	struct mlx4_cmd_mailbox *mailbox;
	struct mlx4_mgm *mgm;
	u32 members_count;
	u16 hash;
	int index, prev;
	int link = 0;
	int i;
	int err;

	mailbox = mlx4_alloc_cmd_mailbox(dev);
	if (IS_ERR(mailbox))
	return PTR_ERR(mailbox);
	mgm = mailbox->buf;

	mutex_lock(&priv->mcg_table.mutex);

	err = find_mgm(dev, gid, mailbox, &hash, &prev, &index);
	if (err)
	goto out;

	if (index != -1) {
	if (!memcmp(mgm->gid, zero_gid, 16))
	memcpy(mgm->gid, gid, 16);
	} else {
	link = 1;

	index = mlx4_bitmap_alloc(&priv->mcg_table.bitmap);
	if (index == -1) {
	mlx4_err(dev, "No AMGM entries left\n");
	err = -ENOMEM;
	goto out;
	}
	index += dev->caps.num_mgms;

	memset(mgm, 0, sizeof *mgm);
	memcpy(mgm->gid, gid, 16);
	}

	members_count = be32_to_cpu(mgm->members_count);
	if (members_count == MLX4_QP_PER_MGM) {
	mlx4_err(dev, "MGM at index %x is full.\n", index);
	err = -ENOMEM;
	goto out;
	}

	for (i = 0; i < members_count; ++i)
	if (mgm->qp[i] == cpu_to_be32(qp->qpn)) {
	mlx4_dbg(dev, "QP %06x already a member of MGM\n", qp->qpn);
	err = 0;
	goto out;
	}

	mgm->qp[members_count++] = cpu_to_be32(qp->qpn);
	mgm->members_count = cpu_to_be32(members_count);

	err = mlx4_WRITE_MCG(dev, index, mailbox);
	if (err)
	goto out;

	if (!link)
	goto out;

	err = mlx4_READ_MCG(dev, prev, mailbox);
	if (err)
	goto out;

	mgm->next_gid_index = cpu_to_be32(index << 6);

	err = mlx4_WRITE_MCG(dev, prev, mailbox);
	if (err)
	goto out;

	out:
	if (err && link && index != -1) {
	if (index < dev->caps.num_mgms)
	mlx4_warn(dev, "Got AMGM index %d < %d",
	index, dev->caps.num_mgms);
	else
	mlx4_bitmap_free(&priv->mcg_table.bitmap,
	index - dev->caps.num_mgms);
	}
	mutex_unlock(&priv->mcg_table.mutex);

	mlx4_free_cmd_mailbox(dev, mailbox);
	return err;
	}
	EXPORT_SYMBOL_GPL(mlx4_multicast_attach);

	int mlx4_multicast_detach(struct mlx4_dev dev, struct mlx4_qp qp, u8 gid[16])
	{
	struct mlx4_priv *priv = mlx4_priv(dev);
	struct mlx4_cmd_mailbox *mailbox;
	struct mlx4_mgm *mgm;
	u32 members_count;
	u16 hash;
	int prev, index;
	int i, loc;
	int err;

	mailbox = mlx4_alloc_cmd_mailbox(dev);
	if (IS_ERR(mailbox))
	return PTR_ERR(mailbox);
	mgm = mailbox->buf;

	mutex_lock(&priv->mcg_table.mutex);

	err = find_mgm(dev, gid, mailbox, &hash, &prev, &index);
	if (err)
	goto out;

	if (index == -1) {
	mlx4_err(dev, "MGID %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x "
	"not found\n",
	be16_to_cpu(((__be16 *) gid)[0]),
	be16_to_cpu(((__be16 *) gid)[1]),
	be16_to_cpu(((__be16 *) gid)[2]),
	be16_to_cpu(((__be16 *) gid)[3]),
	be16_to_cpu(((__be16 *) gid)[4]),
	be16_to_cpu(((__be16 *) gid)[5]),
	be16_to_cpu(((__be16 *) gid)[6]),
	be16_to_cpu(((__be16 *) gid)[7]));
	err = -EINVAL;
	goto out;
	}

	members_count = be32_to_cpu(mgm->members_count);
	for (loc = -1, i = 0; i < members_count; ++i)
	if (mgm->qp[i] == cpu_to_be32(qp->qpn))
	loc = i;

	if (loc == -1) {
	mlx4_err(dev, "QP %06x not found in MGM\n", qp->qpn);
	err = -EINVAL;
	goto out;
	}


	mgm->members_count = cpu_to_be32(--members_count);
	mgm->qp[loc] = mgm->qp[i - 1];
	mgm->qp[i - 1] = 0;

	if (i != 1) {
	err = mlx4_WRITE_MCG(dev, index, mailbox);
	goto out;
	}

	if (prev == -1) {
	/* Remove entry from MGM */
	int amgm_index = be32_to_cpu(mgm->next_gid_index) >> 6;
	if (amgm_index) {
	err = mlx4_READ_MCG(dev, amgm_index, mailbox);
	if (err)
	goto out;
	} else
	memset(mgm->gid, 0, 16);

	err = mlx4_WRITE_MCG(dev, index, mailbox);
	if (err)
	goto out;

	if (amgm_index) {
	if (amgm_index < dev->caps.num_mgms)
	mlx4_warn(dev, "MGM entry %d had AMGM index %d < %d",
	index, amgm_index, dev->caps.num_mgms);
	else
	mlx4_bitmap_free(&priv->mcg_table.bitmap,
	amgm_index - dev->caps.num_mgms);
	}
	} else {
	/* Remove entry from AMGM */
	int cur_next_index = be32_to_cpu(mgm->next_gid_index) >> 6;
	err = mlx4_READ_MCG(dev, prev, mailbox);
	if (err)
	goto out;

	mgm->next_gid_index = cpu_to_be32(cur_next_index << 6);

	err = mlx4_WRITE_MCG(dev, prev, mailbox);
	if (err)
	goto out;

	if (index < dev->caps.num_mgms)
	mlx4_warn(dev, "entry %d had next AMGM index %d < %d",
	prev, index, dev->caps.num_mgms);
	else
	mlx4_bitmap_free(&priv->mcg_table.bitmap,
	index - dev->caps.num_mgms);
	}

	out:
	mutex_unlock(&priv->mcg_table.mutex);

	mlx4_free_cmd_mailbox(dev, mailbox);
	return err;
	}
	EXPORT_SYMBOL_GPL(mlx4_multicast_detach);

	int mlx4_init_mcg_table(struct mlx4_dev *dev)
	{
	struct mlx4_priv *priv = mlx4_priv(dev);
	int err;

	err = mlx4_bitmap_init(&priv->mcg_table.bitmap,
	dev->caps.num_amgms, dev->caps.num_amgms - 1, 0);
	if (err)
	return err;

	mutex_init(&priv->mcg_table.mutex);

	return 0;
	}

	void mlx4_cleanup_mcg_table(struct mlx4_dev *dev)
	{
	mlx4_bitmap_cleanup(&mlx4_priv(dev)->mcg_table.bitmap);
	}