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 --- drivers/dma-buf/sync_debug.c | 124 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 drivers/dma-buf/sync_debug.c (limited to 'drivers/dma-buf/sync_debug.c') diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c new file mode 100644 index 000000000..9e5d662cd --- /dev/null +++ b/drivers/dma-buf/sync_debug.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Sync File validation framework and debug information + * + * Copyright (C) 2012 Google, Inc. + */ + +#include +#include "sync_debug.h" + +static struct dentry *dbgfs; + +static LIST_HEAD(sync_timeline_list_head); +static DEFINE_SPINLOCK(sync_timeline_list_lock); + +void sync_timeline_debug_add(struct sync_timeline *obj) +{ + unsigned long flags; + + spin_lock_irqsave(&sync_timeline_list_lock, flags); + list_add_tail(&obj->sync_timeline_list, &sync_timeline_list_head); + spin_unlock_irqrestore(&sync_timeline_list_lock, flags); +} + +void sync_timeline_debug_remove(struct sync_timeline *obj) +{ + unsigned long flags; + + spin_lock_irqsave(&sync_timeline_list_lock, flags); + list_del(&obj->sync_timeline_list); + spin_unlock_irqrestore(&sync_timeline_list_lock, flags); +} + +static const char *sync_status_str(int status) +{ + if (status < 0) + return "error"; + + if (status > 0) + return "signaled"; + + return "active"; +} + +static void sync_print_fence(struct seq_file *s, + struct dma_fence *fence, bool show) +{ + struct sync_timeline *parent = dma_fence_parent(fence); + int status; + + status = dma_fence_get_status_locked(fence); + + seq_printf(s, " %s%sfence %s", + show ? parent->name : "", + show ? "_" : "", + sync_status_str(status)); + + if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags)) { + struct timespec64 ts64 = + ktime_to_timespec64(fence->timestamp); + + seq_printf(s, "@%ptSp", &ts64); + } + + seq_printf(s, ": %lld", fence->seqno); + seq_printf(s, " / %d", parent->value); + seq_putc(s, '\n'); +} + +static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj) +{ + struct list_head *pos; + + seq_printf(s, "%s: %d\n", obj->name, obj->value); + + spin_lock(&obj->lock); /* Caller already disabled IRQ. */ + list_for_each(pos, &obj->pt_list) { + struct sync_pt *pt = container_of(pos, struct sync_pt, link); + sync_print_fence(s, &pt->base, false); + } + spin_unlock(&obj->lock); +} + +static int sync_info_debugfs_show(struct seq_file *s, void *unused) +{ + struct list_head *pos; + + seq_puts(s, "objs:\n--------------\n"); + + spin_lock_irq(&sync_timeline_list_lock); + list_for_each(pos, &sync_timeline_list_head) { + struct sync_timeline *obj = + container_of(pos, struct sync_timeline, + sync_timeline_list); + + sync_print_obj(s, obj); + seq_putc(s, '\n'); + } + spin_unlock_irq(&sync_timeline_list_lock); + + seq_puts(s, "fences:\n--------------\n"); + + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(sync_info_debugfs); + +static __init int sync_debugfs_init(void) +{ + dbgfs = debugfs_create_dir("sync", NULL); + + /* + * The debugfs files won't ever get removed and thus, there is + * no need to protect it against removal races. The use of + * debugfs_create_file_unsafe() is actually safe here. + */ + debugfs_create_file_unsafe("info", 0444, dbgfs, NULL, + &sync_info_debugfs_fops); + debugfs_create_file_unsafe("sw_sync", 0644, dbgfs, NULL, + &sw_sync_debugfs_fops); + + return 0; +} +late_initcall(sync_debugfs_init); -- cgit v1.3.1