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/clocksource/timer-ralink.c | 157 +++++++++++++++++++++++++++++++++++++ 1 file changed, 157 insertions(+) create mode 100644 drivers/clocksource/timer-ralink.c (limited to 'drivers/clocksource/timer-ralink.c') diff --git a/drivers/clocksource/timer-ralink.c b/drivers/clocksource/timer-ralink.c new file mode 100644 index 000000000..68434d9ed --- /dev/null +++ b/drivers/clocksource/timer-ralink.c @@ -0,0 +1,157 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Ralink System Tick Counter driver present on RT3352 and MT7620 SoCs. + * + * Copyright (C) 2013 by John Crispin + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define SYSTICK_FREQ (50 * 1000) + +#define SYSTICK_CONFIG 0x00 +#define SYSTICK_COMPARE 0x04 +#define SYSTICK_COUNT 0x08 + +/* route systick irq to mips irq 7 instead of the r4k-timer */ +#define CFG_EXT_STK_EN 0x2 +/* enable the counter */ +#define CFG_CNT_EN 0x1 + +struct systick_device { + void __iomem *membase; + struct clock_event_device dev; + int irq_requested; + int freq_scale; +}; + +static int systick_set_oneshot(struct clock_event_device *evt); +static int systick_shutdown(struct clock_event_device *evt); + +static int systick_next_event(unsigned long delta, + struct clock_event_device *evt) +{ + struct systick_device *sdev; + u32 count; + + sdev = container_of(evt, struct systick_device, dev); + count = ioread32(sdev->membase + SYSTICK_COUNT); + count = (count + delta) % SYSTICK_FREQ; + iowrite32(count, sdev->membase + SYSTICK_COMPARE); + + return 0; +} + +static void systick_event_handler(struct clock_event_device *dev) +{ + /* noting to do here */ +} + +static irqreturn_t systick_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *dev = (struct clock_event_device *)dev_id; + + dev->event_handler(dev); + + return IRQ_HANDLED; +} + +static struct systick_device systick = { + .dev = { + /* + * cevt-r4k uses 300, make sure systick + * gets used if available + */ + .rating = 310, + .features = CLOCK_EVT_FEAT_ONESHOT, + .set_next_event = systick_next_event, + .set_state_shutdown = systick_shutdown, + .set_state_oneshot = systick_set_oneshot, + .event_handler = systick_event_handler, + }, +}; + +static int systick_shutdown(struct clock_event_device *evt) +{ + struct systick_device *sdev; + + sdev = container_of(evt, struct systick_device, dev); + + if (sdev->irq_requested) + free_irq(systick.dev.irq, &systick.dev); + sdev->irq_requested = 0; + iowrite32(0, systick.membase + SYSTICK_CONFIG); + + return 0; +} + +static int systick_set_oneshot(struct clock_event_device *evt) +{ + const char *name = systick.dev.name; + struct systick_device *sdev; + int irq = systick.dev.irq; + + sdev = container_of(evt, struct systick_device, dev); + + if (!sdev->irq_requested) { + if (request_irq(irq, systick_interrupt, + IRQF_PERCPU | IRQF_TIMER, name, &systick.dev)) + pr_err("Failed to request irq %d (%s)\n", irq, name); + } + sdev->irq_requested = 1; + iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN, + systick.membase + SYSTICK_CONFIG); + + return 0; +} + +static int __init ralink_systick_init(struct device_node *np) +{ + int ret; + + systick.membase = of_iomap(np, 0); + if (!systick.membase) + return -ENXIO; + + systick.dev.name = np->name; + clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60); + systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev); + systick.dev.max_delta_ticks = 0x7fff; + systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev); + systick.dev.min_delta_ticks = 0x3; + systick.dev.irq = irq_of_parse_and_map(np, 0); + if (!systick.dev.irq) { + pr_err("%pOFn: request_irq failed", np); + ret = -EINVAL; + goto err_iounmap; + } + + ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name, + SYSTICK_FREQ, 301, 16, + clocksource_mmio_readl_up); + if (ret) + goto err_free_irq; + + clockevents_register_device(&systick.dev); + + pr_info("%pOFn: running - mult: %d, shift: %d\n", + np, systick.dev.mult, systick.dev.shift); + + return 0; + +err_free_irq: + irq_dispose_mapping(systick.dev.irq); +err_iounmap: + iounmap(systick.membase); + return ret; +} + +TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init); -- cgit v1.3.1