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/misc/issei/main.c | 296 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 296 insertions(+) create mode 100644 drivers/misc/issei/main.c (limited to 'drivers/misc/issei/main.c') diff --git a/drivers/misc/issei/main.c b/drivers/misc/issei/main.c new file mode 100644 index 000000000..5987fb340 --- /dev/null +++ b/drivers/misc/issei/main.c @@ -0,0 +1,296 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023-2026 Intel Corporation */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "cdev.h" +#include "fw_client.h" +#include "host_client.h" +#include "ham.h" +#include "issei_dev.h" + +static void issei_rst_state_set(struct issei_device *idev, enum issei_rst_state state) +{ + idev->rst_state = state; + /* wake up the thread */ + if (waitqueue_active(&idev->wait_rst_state)) + wake_up(&idev->wait_rst_state); +} + +static int issei_reset(struct issei_device *idev) +{ + int ret; + + idev->ops->irq_clear(idev); + + issei_cl_all_disconnect(idev); + issei_fw_cl_remove_all(idev); + /* No need to check for overflow here, the counter is used only for info */ + idev->all_reset_count++; + ret = idev->ops->hw_reset(idev, !idev->power_down); + issei_dmam_setup(idev); + if (ret) { + dev_err(&idev->dev, "hw_reset failed ret = %d\n", ret); + return ret; + } + + if (idev->power_down) { + dev_dbg(&idev->dev, "powering down: end of reset\n"); + issei_rst_state_set(idev, ISSEI_RST_STATE_DISABLED); + return -ENODEV; + } + return 0; +} + +static int issei_process_read_msg(struct issei_device *idev) +{ + struct issei_dma_data data = {}; + int ret; + + ret = issei_dma_read(idev, &data); + if (ret) + return ret; + + dev_dbg(&idev->dev, "Processing response %u %u %u %u\n", data.fw_id, data.host_id, + data.status, data.length); + if (data.status != HAMS_SUCCESS) { + dev_err(&idev->dev, "Command failed with status 0x%02X", data.status); + kfree(data.buf); + ret = -EIO; + } else { + if (issei_is_ham_rsp(data.fw_id, data.host_id)) + ret = issei_ham_process_ham_rsp(idev, data.buf, data.length); + else + ret = issei_cl_read_buf(idev, data.fw_id, data.host_id, + data.buf, data.length); + } + idev->ops->irq_write_generate(idev); + return ret; +} + +static int issei_process_write_msg(struct issei_device *idev) +{ + if (idev->rst_state != ISSEI_RST_STATE_DONE) + return 0; + + return issei_cl_write_from_queue(idev); +} + +static int issei_process_thread(void *_dev) +{ + long timeout, old_timeout = MAX_SCHEDULE_TIMEOUT; + struct issei_device *idev = _dev; + int ret; + + while (!kthread_should_stop()) { + dev_dbg(&idev->dev, "process_work in %d\n", idev->rst_state); + if (!idev->ops->hw_is_ready(idev) && idev->rst_state > ISSEI_RST_STATE_HW_READY) { + if (!idev->power_down) + dev_dbg(&idev->dev, "HW not ready, resetting\n"); + idev->rst_state = ISSEI_RST_STATE_INIT; + } + if (idev->power_down) + idev->rst_state = ISSEI_RST_STATE_INIT; + WRITE_ONCE(idev->has_data, false); + dev_dbg(&idev->dev, "reset_step in %d\n", idev->rst_state); + timeout = MAX_SCHEDULE_TIMEOUT; + ret = 0; + switch (idev->rst_state) { + case ISSEI_RST_STATE_DISABLED: + if (idev->power_down) { + dev_dbg(&idev->dev, "Interrupt in power down?\n"); + break; + } + idev->rst_state = ISSEI_RST_STATE_INIT; + fallthrough; + + case ISSEI_RST_STATE_INIT: + idev->ops->irq_clear(idev); + idev->ops->irq_sync(idev); + + if (!idev->power_down) { + idev->reset_count++; + if (idev->reset_count > ISSEI_MAX_CONSEC_RESET) { + dev_err(&idev->dev, "reset: reached maximal consecutive resets: disabling the device\n"); + issei_rst_state_set(idev, ISSEI_RST_STATE_DISABLED); + break; + } + } + + ret = issei_reset(idev); + if (idev->power_down) { + dev_dbg(&idev->dev, "Powering down\n"); + return 0; + } + if (ret) + break; + + idev->rst_state = ISSEI_RST_STATE_HW_READY; + timeout = msecs_to_jiffies(ISSEI_RST_HW_READY_TIMEOUT_MSEC); + break; + + case ISSEI_RST_STATE_HW_READY: + if (!idev->ops->hw_is_ready(idev)) { + dev_dbg(&idev->dev, "HW is not ready?\n"); + timeout = old_timeout; + break; + } + + dev_dbg(&idev->dev, "HW is ready\n"); + idev->ops->hw_reset_release(idev); + idev->ops->host_set_ready(idev); + ret = idev->ops->setup_message_send(idev); + if (ret) + break; + + idev->rst_state = ISSEI_RST_STATE_SETUP; + timeout = msecs_to_jiffies(ISSEI_RST_STEP_TIMEOUT_MSEC); + break; + + case ISSEI_RST_STATE_SETUP: + ret = idev->ops->setup_message_recv(idev); + if (ret) { + if (ret == -ENODATA) { + ret = 0; + timeout = old_timeout; + } + } else { + timeout = msecs_to_jiffies(ISSEI_RST_STEP_TIMEOUT_MSEC); + ret = issei_ham_send_start_req(idev); + idev->rst_state = ISSEI_RST_STATE_START; + } + break; + + case ISSEI_RST_STATE_START: + ret = issei_process_read_msg(idev); + if (!ret) { + timeout = msecs_to_jiffies(ISSEI_RST_STEP_TIMEOUT_MSEC); + idev->rst_state = ISSEI_RST_STATE_CLIENT_ENUM; + } else if (ret == -ENODATA) { + ret = 0; + timeout = old_timeout; + } + break; + + case ISSEI_RST_STATE_CLIENT_ENUM: + ret = issei_process_read_msg(idev); + if (ret) { + if (ret == -ENODATA) { + ret = 0; + timeout = old_timeout; + } + } else { + idev->reset_count = 0; + idev->rst_state = ISSEI_RST_STATE_DONE; + dev_dbg(&idev->dev, "Reset finished successfully\n"); + } + break; + + case ISSEI_RST_STATE_DONE: + ret = issei_process_read_msg(idev); + if (ret != 0 && ret != -ENODATA) + break; + + ret = issei_process_write_msg(idev); + break; + } + + if (ret) { + dev_warn(&idev->dev, "Process failed ret = %d\n", ret); + idev->rst_state = ISSEI_RST_STATE_INIT; + continue; + } + + /* + * Every thread that has data to process sets the 'has_data' flag and + * triggers the wait queue. + * The processing thread, in each loop iteration, resets 'has_data' + * and processes all available data. + * + * After processing, the thread waits for 'has_data' to be set again. + * + * If the wait function times out but 'has_data' becomes 1 before + * the subsequent atomic read check, this is acceptable from a flow + * perspective - the thread will continue processing the data. + * + * The 'has_data' flag cannot become 0 between the wait function and + * the atomic read check, since only this thread is allowed to reset it to 0. + */ + + old_timeout = wait_event_interruptible_timeout(idev->wait_has_data, + READ_ONCE(idev->has_data), + timeout); + if (idev->rst_state == ISSEI_RST_STATE_DISABLED) + continue; + + if (!READ_ONCE(idev->has_data)) { + dev_warn(&idev->dev, "Timed out at state %d, resetting\n", + idev->rst_state); + idev->rst_state = ISSEI_RST_STATE_INIT; + } + } + + return 0; +} + +/** + * issei_start - configure HW device and start processing thread. + * @idev: the device structure + * + * Return: 0 on success, < 0 on failure + */ +int issei_start(struct issei_device *idev) +{ + int ret; + + idev->power_down = false; + + ret = issei_dmam_setup(idev); + if (ret) + return ret; + + idev->ops->irq_clear(idev); + + ret = idev->ops->hw_config(idev); + if (ret) + return ret; + + idev->process_thread = kthread_run(issei_process_thread, idev, + "kisseiprocess/%s", dev_name(&idev->dev)); + if (IS_ERR(idev->process_thread)) { + ret = PTR_ERR(idev->process_thread); + dev_err(&idev->dev, "unable to create process thread. ret = %d\n", ret); + return ret; + } + + issei_poke_process_thread(idev); + return 0; +} +EXPORT_SYMBOL_GPL(issei_start); + +/** + * issei_stop - stop interrupts and processing thread. + * @idev: the device structure + */ +void issei_stop(struct issei_device *idev) +{ + idev->power_down = true; + + idev->ops->irq_clear(idev); + idev->ops->irq_sync(idev); + + issei_poke_process_thread(idev); + + wait_event_timeout(idev->wait_rst_state, + (idev->rst_state == ISSEI_RST_STATE_DISABLED), + msecs_to_jiffies(ISSEI_STOP_TIMEOUT_MSEC)); + kthread_stop(idev->process_thread); +} +EXPORT_SYMBOL_GPL(issei_stop); -- cgit v1.3.1