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/mtd/maps/plat-ram.c | 218 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 218 insertions(+) create mode 100644 drivers/mtd/maps/plat-ram.c (limited to 'drivers/mtd/maps/plat-ram.c') diff --git a/drivers/mtd/maps/plat-ram.c b/drivers/mtd/maps/plat-ram.c new file mode 100644 index 000000000..816111031 --- /dev/null +++ b/drivers/mtd/maps/plat-ram.c @@ -0,0 +1,218 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* drivers/mtd/maps/plat-ram.c + * + * (c) 2004-2005 Simtec Electronics + * http://www.simtec.co.uk/products/SWLINUX/ + * Ben Dooks + * + * Generic platform device based RAM map +*/ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#include + +/* private structure for each mtd platform ram device created */ + +struct platram_info { + struct device *dev; + struct mtd_info *mtd; + struct map_info map; + struct platdata_mtd_ram *pdata; +}; + +/* to_platram_info() + * + * device private data to struct platram_info conversion +*/ + +static inline struct platram_info *to_platram_info(struct platform_device *dev) +{ + return platform_get_drvdata(dev); +} + +/* platram_setrw + * + * call the platform device's set rw/ro control + * + * to = 0 => read-only + * = 1 => read-write +*/ + +static inline void platram_setrw(struct platram_info *info, int to) +{ + if (info->pdata == NULL) + return; + + if (info->pdata->set_rw != NULL) + (info->pdata->set_rw)(info->dev, to); +} + +/* platram_remove + * + * called to remove the device from the driver's control +*/ + +static void platram_remove(struct platform_device *pdev) +{ + struct platram_info *info = to_platram_info(pdev); + + dev_dbg(&pdev->dev, "removing device\n"); + + if (info == NULL) + return; + + if (info->mtd) { + mtd_device_unregister(info->mtd); + map_destroy(info->mtd); + } + + /* ensure ram is left read-only */ + + platram_setrw(info, PLATRAM_RO); + + kfree(info); +} + +/* platram_probe + * + * called from device drive system when a device matching our + * driver is found. +*/ + +static int platram_probe(struct platform_device *pdev) +{ + struct platdata_mtd_ram *pdata; + struct platram_info *info; + struct resource *res; + int err = 0; + + dev_dbg(&pdev->dev, "probe entered\n"); + + if (dev_get_platdata(&pdev->dev) == NULL) { + dev_err(&pdev->dev, "no platform data supplied\n"); + err = -ENOENT; + goto exit_error; + } + + pdata = dev_get_platdata(&pdev->dev); + + info = kzalloc_obj(*info); + if (info == NULL) { + err = -ENOMEM; + goto exit_error; + } + + platform_set_drvdata(pdev, info); + + info->dev = &pdev->dev; + info->pdata = pdata; + + /* get the resource for the memory mapping */ + info->map.virt = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(info->map.virt)) { + err = PTR_ERR(info->map.virt); + goto exit_free; + } + + dev_dbg(&pdev->dev, "got platform resource %p (0x%llx)\n", res, + (unsigned long long)res->start); + + /* setup map parameters */ + + info->map.phys = res->start; + info->map.size = resource_size(res); + info->map.name = pdata->mapname != NULL ? + (char *)pdata->mapname : (char *)pdev->name; + info->map.bankwidth = pdata->bankwidth; + + dev_dbg(&pdev->dev, "virt %p, %lu bytes\n", info->map.virt, info->map.size); + + simple_map_init(&info->map); + + dev_dbg(&pdev->dev, "initialised map, probing for mtd\n"); + + /* probe for the right mtd map driver + * supplied by the platform_data struct */ + + if (pdata->map_probes) { + const char * const *map_probes = pdata->map_probes; + + for ( ; !info->mtd && *map_probes; map_probes++) + info->mtd = do_map_probe(*map_probes , &info->map); + } + /* fallback to map_ram */ + else + info->mtd = do_map_probe("map_ram", &info->map); + + if (info->mtd == NULL) { + dev_err(&pdev->dev, "failed to probe for map_ram\n"); + err = -ENOMEM; + goto exit_free; + } + + info->mtd->dev.parent = &pdev->dev; + + platram_setrw(info, PLATRAM_RW); + + /* check to see if there are any available partitions, or whether + * to add this device whole */ + + err = mtd_device_parse_register(info->mtd, pdata->probes, NULL, + pdata->partitions, + pdata->nr_partitions); + if (err) { + dev_err(&pdev->dev, "failed to register mtd device\n"); + goto exit_free; + } + + dev_info(&pdev->dev, "registered mtd device\n"); + + if (pdata->nr_partitions) { + /* add the whole device. */ + err = mtd_device_register(info->mtd, NULL, 0); + if (err) { + dev_err(&pdev->dev, + "failed to register the entire device\n"); + goto exit_free; + } + } + + return 0; + + exit_free: + platram_remove(pdev); + exit_error: + return err; +} + +/* device driver info */ + +/* work with hotplug and coldplug */ +MODULE_ALIAS("platform:mtd-ram"); + +static struct platform_driver platram_driver = { + .probe = platram_probe, + .remove = platram_remove, + .driver = { + .name = "mtd-ram", + }, +}; + +module_platform_driver(platram_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Ben Dooks "); +MODULE_DESCRIPTION("MTD platform RAM map driver"); -- cgit v1.3.1