From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDA30C43331 for ; Thu, 26 Mar 2020 03:52:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC2AD20737 for ; Thu, 26 Mar 2020 03:52:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727751AbgCZDwX (ORCPT ); Wed, 25 Mar 2020 23:52:23 -0400 Received: from mga12.intel.com ([192.55.52.136]:29077 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727707AbgCZDwQ (ORCPT ); Wed, 25 Mar 2020 23:52:16 -0400 IronPort-SDR: vzjSTTKtTZA4peS9dN5RtEbD9CkFYIwnB8JMlesTlWUfqIB/NujEWvbZSz0BxJrc0GRkZ0A3EE TbSSpJPfuokg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Mar 2020 20:52:15 -0700 IronPort-SDR: TezGHVaCeDGFmqT/vxMuM9Up3n0WNFhfE6dT/J7Ol48qA2xNcxW3lQsognmviO0xokkYwlW6GI y7VmD67LswKA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,306,1580803200"; d="scan'208";a="271028118" Received: from jekeller-desk.amr.corp.intel.com ([10.166.241.33]) by fmsmga004.fm.intel.com with ESMTP; 25 Mar 2020 20:52:13 -0700 From: Jacob Keller To: netdev@vger.kernel.org Cc: Jakub Kicinski , Jiri Pirko , Jacob Keller Subject: [net-next v2 08/11] devlink: track snapshot id usage count using an xarray Date: Wed, 25 Mar 2020 20:51:54 -0700 Message-Id: <20200326035157.2211090-9-jacob.e.keller@intel.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200326035157.2211090-1-jacob.e.keller@intel.com> References: <20200326035157.2211090-1-jacob.e.keller@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Each snapshot created for a devlink region must have an id. These ids are supposed to be unique per "event" that caused the snapshot to be created. Drivers call devlink_region_snapshot_id_get to obtain a new id to use for a new event trigger. The id values are tracked per devlink, so that the same id number can be used if a triggering event creates multiple snapshots on different regions. There is no mechanism for snapshot ids to ever be reused. Introduce an xarray to store the count of how many snapshots are using a given id, replacing the snapshot_id field previously used for picking the next id. The devlink_region_snapshot_id_get() function will use xa_alloc to insert an initial value of 1 value at an available slot between 0 and U32_MAX. The new __devlink_snapshot_id_increment() and __devlink_snapshot_id_decrement() functions will be used to track how many snapshots currently use an id. Drivers must now call devlink_snapshot_id_put() in order to release their reference of the snapshot id after adding region snapshots. By tracking the total number of snapshots using a given id, it is possible for the decrement() function to erase the id from the xarray when it is not in use. With this method, a snapshot id can become reused again once all snapshots that referred to it have been deleted via DEVLINK_CMD_REGION_DEL, and the driver has finished adding snapshots. This work also paves the way to introduce a mechanism for userspace to request a snapshot. Signed-off-by: Jacob Keller --- drivers/net/ethernet/mellanox/mlx4/crdump.c | 3 + drivers/net/netdevsim/dev.c | 5 +- include/net/devlink.h | 4 +- net/core/devlink.c | 130 +++++++++++++++++++- 4 files changed, 134 insertions(+), 8 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/crdump.c b/drivers/net/ethernet/mellanox/mlx4/crdump.c index 792951f6df0d..2700628f1689 100644 --- a/drivers/net/ethernet/mellanox/mlx4/crdump.c +++ b/drivers/net/ethernet/mellanox/mlx4/crdump.c @@ -203,6 +203,9 @@ int mlx4_crdump_collect(struct mlx4_dev *dev) mlx4_crdump_collect_crspace(dev, cr_space, id); mlx4_crdump_collect_fw_health(dev, cr_space, id); + /* Release reference on the snapshot id */ + devlink_region_snapshot_id_put(devlink, id); + crdump_disable_crspace_access(dev, cr_space); iounmap(cr_space); diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c index b851fe63a75d..53ec891659eb 100644 --- a/drivers/net/netdevsim/dev.c +++ b/drivers/net/netdevsim/dev.c @@ -44,6 +44,7 @@ static ssize_t nsim_dev_take_snapshot_write(struct file *file, size_t count, loff_t *ppos) { struct nsim_dev *nsim_dev = file->private_data; + struct devlink *devlink = priv_to_devlink(nsim_dev); void *dummy_data; int err; u32 id; @@ -54,13 +55,15 @@ static ssize_t nsim_dev_take_snapshot_write(struct file *file, get_random_bytes(dummy_data, NSIM_DEV_DUMMY_REGION_SIZE); - err = devlink_region_snapshot_id_get(priv_to_devlink(nsim_dev), &id); + err = devlink_region_snapshot_id_get(devlink, &id); if (err) pr_err("Failed to get snapshot id\n"); return err; } err = devlink_region_snapshot_create(nsim_dev->dummy_region, dummy_data, id); + /* release the snapshot id regardless of errors */ + devlink_region_snapshot_id_put(devlink, id); if (err) { pr_err("Failed to create region snapshot\n"); kfree(dummy_data); diff --git a/include/net/devlink.h b/include/net/devlink.h index 9a46bc7fed90..fb9154060e6e 100644 --- a/include/net/devlink.h +++ b/include/net/devlink.h @@ -18,6 +18,7 @@ #include #include #include +#include struct devlink_ops; @@ -29,13 +30,13 @@ struct devlink { struct list_head resource_list; struct list_head param_list; struct list_head region_list; - u32 snapshot_id; struct list_head reporter_list; struct mutex reporters_lock; /* protects reporter_list */ struct devlink_dpipe_headers *dpipe_headers; struct list_head trap_list; struct list_head trap_group_list; const struct devlink_ops *ops; + struct xarray snapshot_ids; struct device *dev; possible_net_t _net; struct mutex lock; @@ -977,6 +978,7 @@ devlink_region_create(struct devlink *devlink, u32 region_max_snapshots, u64 region_size); void devlink_region_destroy(struct devlink_region *region); int devlink_region_snapshot_id_get(struct devlink *devlink, u32 *id); +void devlink_region_snapshot_id_put(struct devlink *devlink, u32 id); int devlink_region_snapshot_create(struct devlink_region *region, u8 *data, u32 snapshot_id); int devlink_info_serial_number_put(struct devlink_info_req *req, diff --git a/net/core/devlink.c b/net/core/devlink.c index 77341c65868f..d89eaac0a101 100644 --- a/net/core/devlink.c +++ b/net/core/devlink.c @@ -3768,6 +3768,83 @@ static void devlink_nl_region_notify(struct devlink_region *region, nlmsg_free(msg); } +/** + * __devlink_snapshot_id_increment - Increment number of snapshots using an id + * @devlink: devlink instance + * @id: the snapshot id + * + * Track when a new snapshot begins using an id. Load the count for the + * given id from the snapshot xarray, increment it, and store it back. + * + * Called when a new snapshot is created with the given id. + * + * The id *must* have been previously allocated by + * devlink_region_snapshot_id_get(). + * + * Returns 0 on success, or an error on failure. + */ +static int __devlink_snapshot_id_increment(struct devlink *devlink, u32 id) +{ + unsigned long count; + void *p; + + lockdep_assert_held(&devlink->lock); + + p = xa_load(&devlink->snapshot_ids, id); + if (WARN_ON(!p)) + return -EINVAL; + + if (WARN_ON(!xa_is_value(p))) + return -EINVAL; + + count = xa_to_value(p); + count++; + + return xa_err(xa_store(&devlink->snapshot_ids, id, xa_mk_value(count), + GFP_KERNEL)); +} + +/** + * __devlink_snapshot_id_decrement - Decrease number of snapshots using an id + * @devlink: devlink instance + * @id: the snapshot id + * + * Track when a snapshot is deleted and stops using an id. Load the count + * for the given id from the snapshot xarray, decrement it, and store it + * back. + * + * If the count reaches zero, erase this id from the xarray, freeing it + * up for future re-use by devlink_region_snapshot_id_get(). + * + * Called when a snapshot using the given id is deleted, and when the + * initial allocator of the id is finished using it. + */ +static void __devlink_snapshot_id_decrement(struct devlink *devlink, u32 id) +{ + unsigned long count; + void *p; + + lockdep_assert_held(&devlink->lock); + + p = xa_load(&devlink->snapshot_ids, id); + if (WARN_ON(!p)) + return; + + if (WARN_ON(!xa_is_value(p))) + return; + + count = xa_to_value(p); + + if (count > 1) { + count--; + xa_store(&devlink->snapshot_ids, id, xa_mk_value(count), + GFP_KERNEL); + } else { + /* If this was the last user, we can erase this id */ + xa_erase(&devlink->snapshot_ids, id); + } +} + /** * __devlink_region_snapshot_id_get - get snapshot ID * @devlink: devlink instance @@ -3776,17 +3853,20 @@ static void devlink_nl_region_notify(struct devlink_region *region, * Allocates a new snapshot id. Returns zero on success, or a negative * error on failure. Must be called while holding the devlink instance * lock. + * + * Snapshot IDs are tracked using an xarray which stores the number of + * users of the snapshot id. + * + * Note that the caller of this function counts as a 'user', in order to + * avoid race conditions. The caller must release its hold on the + * snapshot by using devlink_region_snapshot_id_put. */ static int __devlink_region_snapshot_id_get(struct devlink *devlink, u32 *id) { lockdep_assert_held(&devlink->lock); - if (devlink->snapshot_id >= U32_MAX) - return -ENOSPC; - - *id = ++devlink->snapshot_id; - - return 0; + return xa_alloc(&devlink->snapshot_ids, id, xa_mk_value(1), + xa_limit_32b, GFP_KERNEL); } /** @@ -3809,6 +3889,7 @@ __devlink_region_snapshot_create(struct devlink_region *region, { struct devlink *devlink = region->devlink; struct devlink_snapshot *snapshot; + int err; lockdep_assert_held(&devlink->lock); @@ -3823,6 +3904,10 @@ __devlink_region_snapshot_create(struct devlink_region *region, if (!snapshot) return -ENOMEM; + err = __devlink_snapshot_id_increment(devlink, snapshot_id); + if (err) + goto id_increment_failure; + snapshot->id = snapshot_id; snapshot->region = region; snapshot->data = data; @@ -3833,15 +3918,24 @@ __devlink_region_snapshot_create(struct devlink_region *region, devlink_nl_region_notify(region, snapshot, DEVLINK_CMD_REGION_NEW); return 0; + +id_increment_failure: + kfree(snapshot); + return err; } static void devlink_region_snapshot_del(struct devlink_region *region, struct devlink_snapshot *snapshot) { + struct devlink *devlink = region->devlink; + + lockdep_assert_held(&devlink->lock); + devlink_nl_region_notify(region, snapshot, DEVLINK_CMD_REGION_DEL); region->cur_snapshots--; list_del(&snapshot->list); region->ops->destructor(snapshot->data); + __devlink_snapshot_id_decrement(devlink, snapshot->id); kfree(snapshot); } @@ -6494,6 +6588,7 @@ struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size) if (!devlink) return NULL; devlink->ops = ops; + xa_init_flags(&devlink->snapshot_ids, XA_FLAGS_ALLOC); __devlink_net_set(devlink, &init_net); INIT_LIST_HEAD(&devlink->port_list); INIT_LIST_HEAD(&devlink->sb_list); @@ -6598,6 +6693,8 @@ void devlink_free(struct devlink *devlink) WARN_ON(!list_empty(&devlink->sb_list)); WARN_ON(!list_empty(&devlink->port_list)); + xa_destroy(&devlink->snapshot_ids); + kfree(devlink); } EXPORT_SYMBOL_GPL(devlink_free); @@ -7789,6 +7886,9 @@ EXPORT_SYMBOL_GPL(devlink_region_destroy); * Driver should use the same id for multiple snapshots taken * on multiple regions at the same time/by the same trigger. * + * The caller of this function must use devlink_region_snapshot_id_put + * when finished creating regions using this id. + * * Returns zero on success, or a negative error code on failure. * * @devlink: devlink @@ -7806,6 +7906,24 @@ int devlink_region_snapshot_id_get(struct devlink *devlink, u32 *id) } EXPORT_SYMBOL_GPL(devlink_region_snapshot_id_get); +/** + * devlink_region_snapshot_id_put - put snapshot ID reference + * + * This should be called by a driver after finishing creating snapshots + * with an id. Doing so ensures that the ID can later be released in the + * event that all snapshots using it have been destroyed. + * + * @devlink: devlink + * @id: id to release reference on + */ +void devlink_region_snapshot_id_put(struct devlink *devlink, u32 id) +{ + mutex_lock(&devlink->lock); + __devlink_snapshot_id_decrement(devlink, id); + mutex_unlock(&devlink->lock); +} +EXPORT_SYMBOL_GPL(devlink_region_snapshot_id_put); + /** * devlink_region_snapshot_create - create a new snapshot * This will add a new snapshot of a region. The snapshot -- 2.24.1