From 7874eeacfa42177565c01d5198726671acf7adf2 Mon Sep 17 00:00:00 2001 From: Jacob Moroni Date: Mon, 12 Jan 2026 02:00:06 +0000 Subject: [PATCH] RDMA/iwcm: Fix workqueue list corruption by removing work_list The commit e1168f0 ("RDMA/iwcm: Simplify cm_event_handler()") changed the work submission logic to unconditionally call queue_work() with the expectation that queue_work() would have no effect if work was already pending. The problem is that a free list of struct iwcm_work is used (for which struct work_struct is embedded), so each call to queue_work() is basically unique and therefore does indeed queue the work. This causes a problem in the work handler which walks the work_list until it's empty to process entries. This means that a single run of the work handler could process item N+1 and release it back to the free list while the actual workqueue entry is still queued. It could then get reused (INIT_WORK...) and lead to list corruption in the workqueue logic. Fix this by just removing the work_list. The workqueue already does this for us. This fixes the following error that was observed when stress testing with ucmatose on an Intel E830 in iWARP mode: [ 151.465780] list_del corruption. next->prev should be ffff9f0915c69c08, but was ffff9f0a1116be08. (next=ffff9f0a15b11c08) [ 151.466639] ------------[ cut here ]------------ [ 151.466986] kernel BUG at lib/list_debug.c:67! [ 151.467349] Oops: invalid opcode: 0000 [#1] SMP NOPTI [ 151.467753] CPU: 14 UID: 0 PID: 2306 Comm: kworker/u64:18 Not tainted 6.19.0-rc4+ #1 PREEMPT(voluntary) [ 151.468466] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 151.469192] Workqueue: 0x0 (iw_cm_wq) [ 151.469478] RIP: 0010:__list_del_entry_valid_or_report+0xf0/0x100 [ 151.469942] Code: c7 58 5f 4c b2 e8 10 50 aa ff 0f 0b 48 89 ef e8 36 57 cb ff 48 8b 55 08 48 89 e9 48 89 de 48 c7 c7 a8 5f 4c b2 e8 f0 4f aa ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 [ 151.471323] RSP: 0000:ffffb15644e7bd68 EFLAGS: 00010046 [ 151.471712] RAX: 000000000000006d RBX: ffff9f0915c69c08 RCX: 0000000000000027 [ 151.472243] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9f0a37d9c600 [ 151.472768] RBP: ffff9f0a15b11c08 R08: 0000000000000000 R09: c0000000ffff7fff [ 151.473294] R10: 0000000000000001 R11: ffffb15644e7bba8 R12: ffff9f092339ee68 [ 151.473817] R13: ffff9f0900059c28 R14: ffff9f092339ee78 R15: 0000000000000000 [ 151.474344] FS: 0000000000000000(0000) GS:ffff9f0a847b5000(0000) knlGS:0000000000000000 [ 151.474934] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 151.475362] CR2: 0000559e233a9088 CR3: 000000020296b004 CR4: 0000000000770ef0 [ 151.475895] PKRU: 55555554 [ 151.476118] Call Trace: [ 151.476331] [ 151.476497] move_linked_works+0x49/0xa0 [ 151.476792] __pwq_activate_work.isra.46+0x2f/0xa0 [ 151.477151] pwq_dec_nr_in_flight+0x1e0/0x2f0 [ 151.477479] process_scheduled_works+0x1c8/0x410 [ 151.477823] worker_thread+0x125/0x260 [ 151.478108] ? __pfx_worker_thread+0x10/0x10 [ 151.478430] kthread+0xfe/0x240 [ 151.478671] ? __pfx_kthread+0x10/0x10 [ 151.478955] ? __pfx_kthread+0x10/0x10 [ 151.479240] ret_from_fork+0x208/0x270 [ 151.479523] ? __pfx_kthread+0x10/0x10 [ 151.479806] ret_from_fork_asm+0x1a/0x30 [ 151.480103] Fixes: e1168f09b331 ("RDMA/iwcm: Simplify cm_event_handler()") Signed-off-by: Jacob Moroni Link: https://patch.msgid.link/20260112020006.1352438-1-jmoroni@google.com Reviewed-by: Bart Van Assche Signed-off-by: Leon Romanovsky --- drivers/infiniband/core/iwcm.c | 56 +++++++++++++--------------------- drivers/infiniband/core/iwcm.h | 1 - 2 files changed, 21 insertions(+), 36 deletions(-) diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c index 62410578dec37..eb942ab9c4055 100644 --- a/drivers/infiniband/core/iwcm.c +++ b/drivers/infiniband/core/iwcm.c @@ -95,7 +95,6 @@ static struct workqueue_struct *iwcm_wq; struct iwcm_work { struct work_struct work; struct iwcm_id_private *cm_id; - struct list_head list; struct iw_cm_event event; struct list_head free_list; }; @@ -178,7 +177,6 @@ static int alloc_work_entries(struct iwcm_id_private *cm_id_priv, int count) return -ENOMEM; } work->cm_id = cm_id_priv; - INIT_LIST_HEAD(&work->list); put_work(work); } return 0; @@ -213,7 +211,6 @@ static void free_cm_id(struct iwcm_id_private *cm_id_priv) static bool iwcm_deref_id(struct iwcm_id_private *cm_id_priv) { if (refcount_dec_and_test(&cm_id_priv->refcount)) { - BUG_ON(!list_empty(&cm_id_priv->work_list)); free_cm_id(cm_id_priv); return true; } @@ -260,7 +257,6 @@ struct iw_cm_id *iw_create_cm_id(struct ib_device *device, refcount_set(&cm_id_priv->refcount, 1); init_waitqueue_head(&cm_id_priv->connect_wait); init_completion(&cm_id_priv->destroy_comp); - INIT_LIST_HEAD(&cm_id_priv->work_list); INIT_LIST_HEAD(&cm_id_priv->work_free_list); return &cm_id_priv->id; @@ -1007,13 +1003,13 @@ static int process_event(struct iwcm_id_private *cm_id_priv, } /* - * Process events on the work_list for the cm_id. If the callback - * function requests that the cm_id be deleted, a flag is set in the - * cm_id flags to indicate that when the last reference is - * removed, the cm_id is to be destroyed. This is necessary to - * distinguish between an object that will be destroyed by the app - * thread asleep on the destroy_comp list vs. an object destroyed - * here synchronously when the last reference is removed. + * Process events for the cm_id. If the callback function requests + * that the cm_id be deleted, a flag is set in the cm_id flags to + * indicate that when the last reference is removed, the cm_id is + * to be destroyed. This is necessary to distinguish between an + * object that will be destroyed by the app thread asleep on the + * destroy_comp list vs. an object destroyed here synchronously + * when the last reference is removed. */ static void cm_work_handler(struct work_struct *_work) { @@ -1024,35 +1020,26 @@ static void cm_work_handler(struct work_struct *_work) int ret = 0; spin_lock_irqsave(&cm_id_priv->lock, flags); - while (!list_empty(&cm_id_priv->work_list)) { - work = list_first_entry(&cm_id_priv->work_list, - struct iwcm_work, list); - list_del_init(&work->list); - levent = work->event; - put_work(work); - spin_unlock_irqrestore(&cm_id_priv->lock, flags); - - if (!test_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags)) { - ret = process_event(cm_id_priv, &levent); - if (ret) { - destroy_cm_id(&cm_id_priv->id); - WARN_ON_ONCE(iwcm_deref_id(cm_id_priv)); - } - } else - pr_debug("dropping event %d\n", levent.event); - if (iwcm_deref_id(cm_id_priv)) - return; - spin_lock_irqsave(&cm_id_priv->lock, flags); - } + levent = work->event; + put_work(work); spin_unlock_irqrestore(&cm_id_priv->lock, flags); + + if (!test_bit(IWCM_F_DROP_EVENTS, &cm_id_priv->flags)) { + ret = process_event(cm_id_priv, &levent); + if (ret) { + destroy_cm_id(&cm_id_priv->id); + WARN_ON_ONCE(iwcm_deref_id(cm_id_priv)); + } + } else + pr_debug("dropping event %d\n", levent.event); + if (iwcm_deref_id(cm_id_priv)) + return; } /* * This function is called on interrupt context. Schedule events on * the iwcm_wq thread to allow callback functions to downcall into - * the CM and/or block. Events are queued to a per-CM_ID - * work_list. If this is the first event on the work_list, the work - * element is also queued on the iwcm_wq thread. + * the CM and/or block. * * Each event holds a reference on the cm_id. Until the last posted * event has been delivered and processed, the cm_id cannot be @@ -1094,7 +1081,6 @@ static int cm_event_handler(struct iw_cm_id *cm_id, } refcount_inc(&cm_id_priv->refcount); - list_add_tail(&work->list, &cm_id_priv->work_list); queue_work(iwcm_wq, &work->work); out: spin_unlock_irqrestore(&cm_id_priv->lock, flags); diff --git a/drivers/infiniband/core/iwcm.h b/drivers/infiniband/core/iwcm.h index bf74639be1287..b56fb12edece4 100644 --- a/drivers/infiniband/core/iwcm.h +++ b/drivers/infiniband/core/iwcm.h @@ -50,7 +50,6 @@ struct iwcm_id_private { struct ib_qp *qp; struct completion destroy_comp; wait_queue_head_t connect_wait; - struct list_head work_list; spinlock_t lock; refcount_t refcount; struct list_head work_free_list; -- 2.47.3