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/hv/hv_debugfs.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 178 insertions(+) create mode 100644 drivers/hv/hv_debugfs.c (limited to 'drivers/hv/hv_debugfs.c') diff --git a/drivers/hv/hv_debugfs.c b/drivers/hv/hv_debugfs.c new file mode 100644 index 000000000..ccf752b66 --- /dev/null +++ b/drivers/hv/hv_debugfs.c @@ -0,0 +1,178 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Authors: + * Branden Bonaby + */ + +#include +#include +#include +#include + +#include "hyperv_vmbus.h" + +static struct dentry *hv_debug_root; + +static int hv_debugfs_delay_get(void *data, u64 *val) +{ + *val = *(u32 *)data; + return 0; +} + +static int hv_debugfs_delay_set(void *data, u64 val) +{ + if (val > 1000) + return -EINVAL; + *(u32 *)data = val; + return 0; +} + +DEFINE_DEBUGFS_ATTRIBUTE(hv_debugfs_delay_fops, hv_debugfs_delay_get, + hv_debugfs_delay_set, "%llu\n"); + +static int hv_debugfs_state_get(void *data, u64 *val) +{ + *val = *(bool *)data; + return 0; +} + +static int hv_debugfs_state_set(void *data, u64 val) +{ + if (val == 1) + *(bool *)data = true; + else if (val == 0) + *(bool *)data = false; + else + return -EINVAL; + return 0; +} + +DEFINE_DEBUGFS_ATTRIBUTE(hv_debugfs_state_fops, hv_debugfs_state_get, + hv_debugfs_state_set, "%llu\n"); + +/* Setup delay files to store test values */ +static int hv_debug_delay_files(struct hv_device *dev, struct dentry *root) +{ + struct vmbus_channel *channel = dev->channel; + char *buffer = "fuzz_test_buffer_interrupt_delay"; + char *message = "fuzz_test_message_delay"; + int *buffer_val = &channel->fuzz_testing_interrupt_delay; + int *message_val = &channel->fuzz_testing_message_delay; + struct dentry *buffer_file, *message_file; + + buffer_file = debugfs_create_file(buffer, 0644, root, + buffer_val, + &hv_debugfs_delay_fops); + if (IS_ERR(buffer_file)) { + pr_debug("debugfs_hyperv: file %s not created\n", buffer); + return PTR_ERR(buffer_file); + } + + message_file = debugfs_create_file(message, 0644, root, + message_val, + &hv_debugfs_delay_fops); + if (IS_ERR(message_file)) { + pr_debug("debugfs_hyperv: file %s not created\n", message); + return PTR_ERR(message_file); + } + + return 0; +} + +/* Setup test state value for vmbus device */ +static int hv_debug_set_test_state(struct hv_device *dev, struct dentry *root) +{ + struct vmbus_channel *channel = dev->channel; + bool *state = &channel->fuzz_testing_state; + char *status = "fuzz_test_state"; + struct dentry *test_state; + + test_state = debugfs_create_file(status, 0644, root, + state, + &hv_debugfs_state_fops); + if (IS_ERR(test_state)) { + pr_debug("debugfs_hyperv: file %s not created\n", status); + return PTR_ERR(test_state); + } + + return 0; +} + +/* Bind hv device to a dentry for debugfs */ +static void hv_debug_set_dir_dentry(struct hv_device *dev, struct dentry *root) +{ + if (hv_debug_root) + dev->debug_dir = root; +} + +/* Create all test dentry's and names for fuzz testing */ +int hv_debug_add_dev_dir(struct hv_device *dev) +{ + const char *device = dev_name(&dev->device); + char *delay_name = "delay"; + struct dentry *delay, *dev_root; + int ret; + + if (!IS_ERR(hv_debug_root)) { + dev_root = debugfs_create_dir(device, hv_debug_root); + if (IS_ERR(dev_root)) { + pr_debug("debugfs_hyperv: hyperv/%s/ not created\n", + device); + return PTR_ERR(dev_root); + } + hv_debug_set_test_state(dev, dev_root); + hv_debug_set_dir_dentry(dev, dev_root); + delay = debugfs_create_dir(delay_name, dev_root); + + if (IS_ERR(delay)) { + pr_debug("debugfs_hyperv: hyperv/%s/%s/ not created\n", + device, delay_name); + return PTR_ERR(delay); + } + ret = hv_debug_delay_files(dev, delay); + + return ret; + } + pr_debug("debugfs_hyperv: hyperv/ not in root debugfs path\n"); + return PTR_ERR(hv_debug_root); +} + +/* Remove dentry associated with released hv device */ +void hv_debug_rm_dev_dir(struct hv_device *dev) +{ + if (!IS_ERR(hv_debug_root)) + debugfs_remove_recursive(dev->debug_dir); +} + +/* Remove all dentrys associated with vmbus testing */ +void hv_debug_rm_all_dir(void) +{ + debugfs_remove_recursive(hv_debug_root); +} + +/* Delay buffer/message reads on a vmbus channel */ +void hv_debug_delay_test(struct vmbus_channel *channel, enum delay delay_type) +{ + struct vmbus_channel *test_channel = channel->primary_channel ? + channel->primary_channel : + channel; + bool state = test_channel->fuzz_testing_state; + + if (state) { + if (delay_type == 0) + udelay(test_channel->fuzz_testing_interrupt_delay); + else + udelay(test_channel->fuzz_testing_message_delay); + } +} + +/* Initialize top dentry for vmbus testing */ +int hv_debug_init(void) +{ + hv_debug_root = debugfs_create_dir("hyperv", NULL); + if (IS_ERR(hv_debug_root)) { + pr_debug("debugfs_hyperv: hyperv/ not created\n"); + return PTR_ERR(hv_debug_root); + } + return 0; +} -- cgit v1.3.1