cregit-Linux how code gets into the kernel

Release 4.7 drivers/net/ethernet/mellanox/mlx5/core/fs_counters.c

/*
 * Copyright (c) 2016, Mellanox Technologies. 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/mlx5/driver.h>
#include <linux/mlx5/fs.h>
#include "mlx5_core.h"
#include "fs_core.h"
#include "fs_cmd.h"


#define MLX5_FC_STATS_PERIOD msecs_to_jiffies(1000)

/* locking scheme:
 *
 * It is the responsibility of the user to prevent concurrent calls or bad
 * ordering to mlx5_fc_create(), mlx5_fc_destroy() and accessing a reference
 * to struct mlx5_fc.
 * e.g en_tc.c is protected by RTNL lock of its caller, and will never call a
 * dump (access to struct mlx5_fc) after a counter is destroyed.
 *
 * access to counter list:
 * - create (user context)
 *   - mlx5_fc_create() only adds to an addlist to be used by
 *     mlx5_fc_stats_query_work(). addlist is protected by a spinlock.
 *   - spawn thread to do the actual destroy
 *
 * - destroy (user context)
 *   - mark a counter as deleted
 *   - spawn thread to do the actual del
 *
 * - dump (user context)
 *   user should not call dump after destroy
 *
 * - query (single thread workqueue context)
 *   destroy/dump - no conflict (see destroy)
 *   query/dump - packets and bytes might be inconsistent (since update is not
 *                atomic)
 *   query/create - no conflict (see create)
 *   since every create/destroy spawn the work, only after necessary time has
 *   elapsed, the thread will actually query the hardware.
 */


static void mlx5_fc_stats_work(struct work_struct *work) { struct mlx5_core_dev *dev = container_of(work, struct mlx5_core_dev, priv.fc_stats.work.work); struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats; unsigned long now = jiffies; struct mlx5_fc *counter; struct mlx5_fc *tmp; int err = 0; spin_lock(&fc_stats->addlist_lock); list_splice_tail_init(&fc_stats->addlist, &fc_stats->list); if (!list_empty(&fc_stats->list)) queue_delayed_work(fc_stats->wq, &fc_stats->work, MLX5_FC_STATS_PERIOD); spin_unlock(&fc_stats->addlist_lock); list_for_each_entry_safe(counter, tmp, &fc_stats->list, list) { struct mlx5_fc_cache *c = &counter->cache; u64 packets; u64 bytes; if (counter->deleted) { list_del(&counter->list); mlx5_cmd_fc_free(dev, counter->id); kfree(counter); continue; } if (time_before(now, fc_stats->next_query)) continue; err = mlx5_cmd_fc_query(dev, counter->id, &packets, &bytes); if (err) { pr_err("Error querying stats for counter id %d\n", counter->id); continue; } if (packets == c->packets) continue; c->lastuse = jiffies; c->packets = packets; c->bytes = bytes; } if (time_after_eq(now, fc_stats->next_query)) fc_stats->next_query = now + MLX5_FC_STATS_PERIOD; }

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struct mlx5_fc *mlx5_fc_create(struct mlx5_core_dev *dev, bool aging) { struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats; struct mlx5_fc *counter; int err; counter = kzalloc(sizeof(*counter), GFP_KERNEL); if (!counter) return ERR_PTR(-ENOMEM); err = mlx5_cmd_fc_alloc(dev, &counter->id); if (err) goto err_out; if (aging) { counter->aging = true; spin_lock(&fc_stats->addlist_lock); list_add(&counter->list, &fc_stats->addlist); spin_unlock(&fc_stats->addlist_lock); mod_delayed_work(fc_stats->wq, &fc_stats->work, 0); } return counter; err_out: kfree(counter); return ERR_PTR(err); }

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void mlx5_fc_destroy(struct mlx5_core_dev *dev, struct mlx5_fc *counter) { struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats; if (!counter) return; if (counter->aging) { counter->deleted = true; mod_delayed_work(fc_stats->wq, &fc_stats->work, 0); return; } mlx5_cmd_fc_free(dev, counter->id); kfree(counter); }

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int mlx5_init_fc_stats(struct mlx5_core_dev *dev) { struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats; INIT_LIST_HEAD(&fc_stats->list); INIT_LIST_HEAD(&fc_stats->addlist); spin_lock_init(&fc_stats->addlist_lock); fc_stats->wq = create_singlethread_workqueue("mlx5_fc"); if (!fc_stats->wq) return -ENOMEM; INIT_DELAYED_WORK(&fc_stats->work, mlx5_fc_stats_work); return 0; }

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void mlx5_cleanup_fc_stats(struct mlx5_core_dev *dev) { struct mlx5_fc_stats *fc_stats = &dev->priv.fc_stats; struct mlx5_fc *counter; struct mlx5_fc *tmp; cancel_delayed_work_sync(&dev->priv.fc_stats.work); destroy_workqueue(dev->priv.fc_stats.wq); dev->priv.fc_stats.wq = NULL; list_splice_tail_init(&fc_stats->addlist, &fc_stats->list); list_for_each_entry_safe(counter, tmp, &fc_stats->list, list) { list_del(&counter->list); mlx5_cmd_fc_free(dev, counter->id); kfree(counter); } }

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void mlx5_fc_query_cached(struct mlx5_fc *counter, u64 *bytes, u64 *packets, u64 *lastuse) { struct mlx5_fc_cache c; c = counter->cache; *bytes = c.bytes - counter->lastbytes; *packets = c.packets - counter->lastpackets; *lastuse = c.lastuse; counter->lastbytes = c.bytes; counter->lastpackets = c.packets; }

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