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/dca/dca-sysfs.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 drivers/dca/dca-sysfs.c (limited to 'drivers/dca/dca-sysfs.c') diff --git a/drivers/dca/dca-sysfs.c b/drivers/dca/dca-sysfs.c new file mode 100644 index 000000000..b915c2b46 --- /dev/null +++ b/drivers/dca/dca-sysfs.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright(c) 2007 - 2009 Intel Corporation. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static const struct class dca_class = { + .name = "dca", +}; +static struct idr dca_idr; +static spinlock_t dca_idr_lock; + +int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot) +{ + struct device *cd; + static int req_count; + + cd = device_create(&dca_class, dca->cd, MKDEV(0, slot + 1), NULL, + "requester%d", req_count++); + return PTR_ERR_OR_ZERO(cd); +} + +void dca_sysfs_remove_req(struct dca_provider *dca, int slot) +{ + device_destroy(&dca_class, MKDEV(0, slot + 1)); +} + +int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev) +{ + struct device *cd; + int ret; + + idr_preload(GFP_KERNEL); + spin_lock(&dca_idr_lock); + + ret = idr_alloc(&dca_idr, dca, 0, 0, GFP_NOWAIT); + if (ret >= 0) + dca->id = ret; + + spin_unlock(&dca_idr_lock); + idr_preload_end(); + if (ret < 0) + return ret; + + cd = device_create(&dca_class, dev, MKDEV(0, 0), NULL, "dca%d", dca->id); + if (IS_ERR(cd)) { + spin_lock(&dca_idr_lock); + idr_remove(&dca_idr, dca->id); + spin_unlock(&dca_idr_lock); + return PTR_ERR(cd); + } + dca->cd = cd; + return 0; +} + +void dca_sysfs_remove_provider(struct dca_provider *dca) +{ + device_unregister(dca->cd); + dca->cd = NULL; + spin_lock(&dca_idr_lock); + idr_remove(&dca_idr, dca->id); + spin_unlock(&dca_idr_lock); +} + +int __init dca_sysfs_init(void) +{ + int err; + + idr_init(&dca_idr); + spin_lock_init(&dca_idr_lock); + + err = class_register(&dca_class); + if (err) { + idr_destroy(&dca_idr); + return err; + } + return 0; +} + +void __exit dca_sysfs_exit(void) +{ + class_unregister(&dca_class); + idr_destroy(&dca_idr); +} + -- cgit v1.3.1