From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- fs/afs/fs_operation.c | 377 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 377 insertions(+) create mode 100644 fs/afs/fs_operation.c (limited to 'fs/afs/fs_operation.c') diff --git a/fs/afs/fs_operation.c b/fs/afs/fs_operation.c new file mode 100644 index 000000000..20801b295 --- /dev/null +++ b/fs/afs/fs_operation.c @@ -0,0 +1,377 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Fileserver-directed operation handling. + * + * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include "internal.h" + +static atomic_t afs_operation_debug_counter; + +/* + * Create an operation against a volume. + */ +struct afs_operation *afs_alloc_operation(struct key *key, struct afs_volume *volume) +{ + struct afs_operation *op; + + _enter(""); + + op = kzalloc_obj(*op); + if (!op) + return ERR_PTR(-ENOMEM); + + if (!key) { + key = afs_request_key(volume->cell); + if (IS_ERR(key)) { + kfree(op); + return ERR_CAST(key); + } + } else { + key_get(key); + } + + op->key = key; + op->volume = afs_get_volume(volume, afs_volume_trace_get_new_op); + op->net = volume->cell->net; + op->cb_v_break = atomic_read(&volume->cb_v_break); + op->pre_volsync.creation = volume->creation_time; + op->pre_volsync.update = volume->update_time; + op->debug_id = atomic_inc_return(&afs_operation_debug_counter); + op->nr_iterations = -1; + afs_op_set_error(op, -EDESTADDRREQ); + + _leave(" = [op=%08x]", op->debug_id); + return op; +} + +struct afs_io_locker { + struct list_head link; + struct task_struct *task; + unsigned long have_lock; +}; + +/* + * Unlock the I/O lock on a vnode. + */ +static void afs_unlock_for_io(struct afs_vnode *vnode) +{ + struct afs_io_locker *locker; + + spin_lock(&vnode->lock); + locker = list_first_entry_or_null(&vnode->io_lock_waiters, + struct afs_io_locker, link); + if (locker) { + list_del(&locker->link); + smp_store_release(&locker->have_lock, 1); /* The unlock barrier. */ + smp_mb__after_atomic(); /* Store have_lock before task state */ + wake_up_process(locker->task); + } else { + clear_bit(AFS_VNODE_IO_LOCK, &vnode->flags); + } + spin_unlock(&vnode->lock); +} + +/* + * Lock the I/O lock on a vnode uninterruptibly. We can't use an ordinary + * mutex as lockdep will complain if we unlock it in the wrong thread. + */ +static void afs_lock_for_io(struct afs_vnode *vnode) +{ + struct afs_io_locker myself = { .task = current, }; + + spin_lock(&vnode->lock); + + if (!test_and_set_bit(AFS_VNODE_IO_LOCK, &vnode->flags)) { + spin_unlock(&vnode->lock); + return; + } + + list_add_tail(&myself.link, &vnode->io_lock_waiters); + spin_unlock(&vnode->lock); + + for (;;) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (smp_load_acquire(&myself.have_lock)) /* The lock barrier */ + break; + schedule(); + } + __set_current_state(TASK_RUNNING); +} + +/* + * Lock the I/O lock on a vnode interruptibly. We can't use an ordinary mutex + * as lockdep will complain if we unlock it in the wrong thread. + */ +static int afs_lock_for_io_interruptible(struct afs_vnode *vnode) +{ + struct afs_io_locker myself = { .task = current, }; + int ret = 0; + + spin_lock(&vnode->lock); + + if (!test_and_set_bit(AFS_VNODE_IO_LOCK, &vnode->flags)) { + spin_unlock(&vnode->lock); + return 0; + } + + list_add_tail(&myself.link, &vnode->io_lock_waiters); + spin_unlock(&vnode->lock); + + for (;;) { + set_current_state(TASK_INTERRUPTIBLE); + if (smp_load_acquire(&myself.have_lock) || /* The lock barrier */ + signal_pending(current)) + break; + schedule(); + } + __set_current_state(TASK_RUNNING); + + /* If we got a signal, try to transfer the lock onto the next + * waiter. + */ + if (unlikely(signal_pending(current))) { + spin_lock(&vnode->lock); + if (myself.have_lock) { + spin_unlock(&vnode->lock); + afs_unlock_for_io(vnode); + } else { + list_del(&myself.link); + spin_unlock(&vnode->lock); + } + ret = -ERESTARTSYS; + } + return ret; +} + +/* + * Lock the vnode(s) being operated upon. + */ +static bool afs_get_io_locks(struct afs_operation *op) +{ + struct afs_vnode *vnode = op->file[0].vnode; + struct afs_vnode *vnode2 = op->file[1].vnode; + + _enter(""); + + if (op->flags & AFS_OPERATION_UNINTR) { + afs_lock_for_io(vnode); + op->flags |= AFS_OPERATION_LOCK_0; + _leave(" = t [1]"); + return true; + } + + if (!vnode2 || !op->file[1].need_io_lock || vnode == vnode2) + vnode2 = NULL; + + if (vnode2 > vnode) + swap(vnode, vnode2); + + if (afs_lock_for_io_interruptible(vnode) < 0) { + afs_op_set_error(op, -ERESTARTSYS); + op->flags |= AFS_OPERATION_STOP; + _leave(" = f [I 0]"); + return false; + } + op->flags |= AFS_OPERATION_LOCK_0; + + if (vnode2) { + if (afs_lock_for_io_interruptible(vnode2) < 0) { + afs_op_set_error(op, -ERESTARTSYS); + op->flags |= AFS_OPERATION_STOP; + afs_unlock_for_io(vnode); + op->flags &= ~AFS_OPERATION_LOCK_0; + _leave(" = f [I 1]"); + return false; + } + op->flags |= AFS_OPERATION_LOCK_1; + } + + _leave(" = t [2]"); + return true; +} + +static void afs_drop_io_locks(struct afs_operation *op) +{ + struct afs_vnode *vnode = op->file[0].vnode; + struct afs_vnode *vnode2 = op->file[1].vnode; + + _enter(""); + + if (op->flags & AFS_OPERATION_LOCK_1) + afs_unlock_for_io(vnode2); + if (op->flags & AFS_OPERATION_LOCK_0) + afs_unlock_for_io(vnode); +} + +static void afs_prepare_vnode(struct afs_operation *op, struct afs_vnode_param *vp, + unsigned int index) +{ + struct afs_vnode *vnode = vp->vnode; + + if (vnode) { + vp->fid = vnode->fid; + vp->dv_before = vnode->status.data_version; + vp->cb_break_before = afs_calc_vnode_cb_break(vnode); + if (vnode->lock_state != AFS_VNODE_LOCK_NONE) + op->flags |= AFS_OPERATION_CUR_ONLY; + if (vp->modification) + set_bit(AFS_VNODE_MODIFYING, &vnode->flags); + } + + if (vp->fid.vnode) + _debug("PREP[%u] {%llx:%llu.%u}", + index, vp->fid.vid, vp->fid.vnode, vp->fid.unique); +} + +/* + * Begin an operation on the fileserver. + * + * Fileserver operations are serialised on the server by vnode, so we serialise + * them here also using the io_lock. + */ +bool afs_begin_vnode_operation(struct afs_operation *op) +{ + struct afs_vnode *vnode = op->file[0].vnode; + + ASSERT(vnode); + + _enter(""); + + if (op->file[0].need_io_lock) + if (!afs_get_io_locks(op)) + return false; + + afs_prepare_vnode(op, &op->file[0], 0); + afs_prepare_vnode(op, &op->file[1], 1); + op->cb_v_break = atomic_read(&op->volume->cb_v_break); + _leave(" = true"); + return true; +} + +/* + * Tidy up a filesystem cursor and unlock the vnode. + */ +void afs_end_vnode_operation(struct afs_operation *op) +{ + _enter(""); + + switch (afs_op_error(op)) { + case -EDESTADDRREQ: + case -EADDRNOTAVAIL: + case -ENETUNREACH: + case -EHOSTUNREACH: + afs_dump_edestaddrreq(op); + break; + } + + afs_drop_io_locks(op); +} + +/* + * Wait for an in-progress operation to complete. + */ +void afs_wait_for_operation(struct afs_operation *op) +{ + _enter(""); + + while (afs_select_fileserver(op)) { + op->call_responded = false; + op->call_error = 0; + op->call_abort_code = 0; + if (test_bit(AFS_SERVER_FL_IS_YFS, &op->server->flags) && + op->ops->issue_yfs_rpc) + op->ops->issue_yfs_rpc(op); + else if (op->ops->issue_afs_rpc) + op->ops->issue_afs_rpc(op); + else + op->call_error = -ENOTSUPP; + + if (op->call) { + afs_wait_for_call_to_complete(op->call); + op->call_abort_code = op->call->abort_code; + op->call_error = op->call->error; + op->call_responded = op->call->responded; + afs_put_call(op->call); + } + } + + if (op->call_responded && op->server) + set_bit(AFS_SERVER_FL_RESPONDING, &op->server->flags); + + if (!afs_op_error(op)) { + _debug("success"); + op->ops->success(op); + } else if (op->cumul_error.aborted) { + if (op->ops->aborted) + op->ops->aborted(op); + } else { + if (op->ops->failed) + op->ops->failed(op); + } + + afs_end_vnode_operation(op); + + if (!afs_op_error(op) && op->ops->edit_dir) { + _debug("edit_dir"); + op->ops->edit_dir(op); + } + _leave(""); +} + +/* + * Dispose of an operation. + */ +int afs_put_operation(struct afs_operation *op) +{ + struct afs_addr_list *alist; + int i, ret = afs_op_error(op); + + _enter("op=%08x,%d", op->debug_id, ret); + + if (op->ops && op->ops->put) + op->ops->put(op); + if (op->file[0].modification) + clear_bit(AFS_VNODE_MODIFYING, &op->file[0].vnode->flags); + if (op->file[1].modification && op->file[1].vnode != op->file[0].vnode) + clear_bit(AFS_VNODE_MODIFYING, &op->file[1].vnode->flags); + if (op->file[0].put_vnode) + iput(&op->file[0].vnode->netfs.inode); + if (op->file[1].put_vnode) + iput(&op->file[1].vnode->netfs.inode); + + if (op->more_files) { + for (i = 0; i < op->nr_files - 2; i++) + if (op->more_files[i].put_vnode) + iput(&op->more_files[i].vnode->netfs.inode); + kvfree(op->more_files); + } + + if (op->estate) { + alist = op->estate->addresses; + if (alist) { + if (op->call_responded && + op->addr_index != alist->preferred && + test_bit(alist->preferred, &op->addr_tried)) + WRITE_ONCE(alist->preferred, op->addr_index); + } + } + + afs_clear_server_states(op); + afs_put_serverlist(op->net, op->server_list); + afs_put_volume(op->volume, afs_volume_trace_put_put_op); + key_put(op->key); + kfree(op); + return ret; +} + +int afs_do_sync_operation(struct afs_operation *op) +{ + afs_begin_vnode_operation(op); + afs_wait_for_operation(op); + return afs_put_operation(op); +} -- cgit v1.3.1