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/acpi/reboot.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 drivers/acpi/reboot.c (limited to 'drivers/acpi/reboot.c') diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c new file mode 100644 index 000000000..b79b7c99c --- /dev/null +++ b/drivers/acpi/reboot.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define pr_fmt(fmt) "ACPI: " fmt + +#include +#include +#include +#include + +#ifdef CONFIG_PCI +static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) +{ + unsigned int devfn; + struct pci_bus *bus0; + + /* The reset register can only live on bus 0. */ + bus0 = pci_find_bus(0, 0); + if (!bus0) + return; + /* Form PCI device/function pair. */ + devfn = PCI_DEVFN((rr->address >> 32) & 0xffff, + (rr->address >> 16) & 0xffff); + pr_debug("Resetting with ACPI PCI RESET_REG.\n"); + /* Write the value that resets us. */ + pci_bus_write_config_byte(bus0, devfn, + (rr->address & 0xffff), reset_value); +} +#else +static inline void acpi_pci_reboot(struct acpi_generic_address *rr, + u8 reset_value) +{ + pr_warn_once("PCI configuration space access is not supported\n"); +} +#endif + +void acpi_reboot(void) +{ + struct acpi_generic_address *rr; + u8 reset_value; + + if (acpi_disabled) + return; + + rr = &acpi_gbl_FADT.reset_register; + + /* ACPI reset register was only introduced with v2 of the FADT */ + + if (acpi_gbl_FADT.header.revision < 2) + return; + + /* Is the reset register supported? The spec says we should be + * checking the bit width and bit offset, but Windows ignores + * these fields */ + if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER)) + return; + + reset_value = acpi_gbl_FADT.reset_value; + + /* The reset register can only exist in I/O, Memory or PCI config space + * on a device on bus 0. */ + switch (rr->space_id) { + case ACPI_ADR_SPACE_PCI_CONFIG: + acpi_pci_reboot(rr, reset_value); + break; + + case ACPI_ADR_SPACE_SYSTEM_MEMORY: + case ACPI_ADR_SPACE_SYSTEM_IO: + pr_debug("ACPI MEMORY or I/O RESET_REG.\n"); + acpi_reset(); + break; + } + + /* + * Some platforms do not shut down immediately after writing to the + * ACPI reset register, and this results in racing with the + * subsequent reboot mechanism. + * + * The 15ms delay has been found to be long enough for the system + * to reboot on the affected platforms. + */ + mdelay(15); +} -- cgit v1.3.1