Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

Make expedited grace periods expedite normal RCU callbacks

Miscellaneous fixes:
 * Improve diagnostic output with character task states.
 * Mark accesses to inform KCSAN of concurrency design.
 * Move from kmalloc() to kmalloc_obj().
 * Documentation updates.
 * Improve handling of RCU deferred quiescent states.
 * Clean up unused function arguments and structure fields.
 * Reduce show_rcu_gp_kthreads() stack space.

Tasks RCU updates:
 * Clean up after SRCU re-implementation of Tasks Trace RCU.
 * Mark accesses to inform KCSAN of concurrency design.
 * Add ->lazy_timer status to diagnostic output.
 * Remove an unnecessary memory barrier.
 * Fix a data race, courtesy of KCSAN.
 * Documentation updates.
 * Convert cond_resched_tasks_rcu_qs() from macro to static inline
   function.

SRCU updates:
 * Add Rust helpers for SRCU.
 * Avoid losing queued work at cleanup_srcu_struct() time.

Torture-test updates:
 * Preparation work for immediate RCU priority deboosting.
 * Test RCU readers from real interrupt handlers (as opposed to softirq).
 * Simplify code through use of cpumask_next_wrap().
 * Improve diagnostic output with character task states.
 * Add rcutorture.nwriters parameter to allow lightweight stall testing,
   and rcutorture.stall_only to make doing so easier.
 * Test an RCU Tasks Trace grace period implying an RCU grace period.
 * Make RCU Tasks Trace torturing track reader batches.
 * Fix a data race, courtesy of KCSAN.
 * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.

3 files changed, 188 insertions, 0 deletions

diff --git a/samples/hidraw/.gitignore b/samples/hidraw/.gitignore
new file mode 100644
index 000000000..5233ab632
--- /dev/null
+++ b/samples/hidraw/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+/hid-example
diff --git a/samples/hidraw/Makefile b/samples/hidraw/Makefile
new file mode 100644
index 000000000..594d989e5
--- /dev/null
+++ b/samples/hidraw/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+userprogs-always-y += hid-example
+
+userccflags += -I usr/include
diff --git a/samples/hidraw/hid-example.c b/samples/hidraw/hid-example.c
new file mode 100644
index 000000000..0f73ace3c
--- /dev/null
+++ b/samples/hidraw/hid-example.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hidraw Userspace Example
+ *
+ * Copyright (c) 2010 Alan Ott <alan@signal11.us>
+ * Copyright (c) 2010 Signal 11 Software
+ *
+ * The code may be used by anyone for any purpose,
+ * and can serve as a starting point for developing
+ * applications using hidraw.
+ */
+
+/* Linux */
+#include <linux/types.h>
+#include <linux/input.h>
+#include <linux/hidraw.h>
+
+/*
+ * Ugly hack to work around failing compilation on systems that don't
+ * yet populate new version of hidraw.h to userspace.
+ */
+#ifndef HIDIOCSFEATURE
+#warning Please have your distro update the userspace kernel headers
+#define HIDIOCSFEATURE(len)    _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x06, len)
+#define HIDIOCGFEATURE(len)    _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x07, len)
+#endif
+
+/* Unix */
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/* C */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+const char *bus_str(int bus);
+
+int main(int argc, char **argv)
+{
+	int fd;
+	int i, res, desc_size = 0;
+	char buf[256];
+	struct hidraw_report_descriptor rpt_desc;
+	struct hidraw_devinfo info;
+	char *device = "/dev/hidraw0";
+
+	if (argc > 1)
+		device = argv[1];
+
+	/* Open the Device with non-blocking reads. In real life,
+	   don't use a hard coded path; use libudev instead. */
+	fd = open(device, O_RDWR|O_NONBLOCK);
+
+	if (fd < 0) {
+		perror("Unable to open device");
+		return 1;
+	}
+
+	memset(&rpt_desc, 0x0, sizeof(rpt_desc));
+	memset(&info, 0x0, sizeof(info));
+	memset(buf, 0x0, sizeof(buf));
+
+	/* Get Report Descriptor Size */
+	res = ioctl(fd, HIDIOCGRDESCSIZE, &desc_size);
+	if (res < 0)
+		perror("HIDIOCGRDESCSIZE");
+	else
+		printf("Report Descriptor Size: %d\n", desc_size);
+
+	/* Get Report Descriptor */
+	rpt_desc.size = desc_size;
+	res = ioctl(fd, HIDIOCGRDESC, &rpt_desc);
+	if (res < 0) {
+		perror("HIDIOCGRDESC");
+	} else {
+		printf("Report Descriptor:\n");
+		for (i = 0; i < rpt_desc.size; i++)
+			printf("%hhx ", rpt_desc.value[i]);
+		puts("\n");
+	}
+
+	/* Get Raw Name */
+	res = ioctl(fd, HIDIOCGRAWNAME(256), buf);
+	if (res < 0)
+		perror("HIDIOCGRAWNAME");
+	else
+		printf("Raw Name: %s\n", buf);
+
+	/* Get Physical Location */
+	res = ioctl(fd, HIDIOCGRAWPHYS(256), buf);
+	if (res < 0)
+		perror("HIDIOCGRAWPHYS");
+	else
+		printf("Raw Phys: %s\n", buf);
+
+	/* Get Raw Info */
+	res = ioctl(fd, HIDIOCGRAWINFO, &info);
+	if (res < 0) {
+		perror("HIDIOCGRAWINFO");
+	} else {
+		printf("Raw Info:\n");
+		printf("\tbustype: %d (%s)\n",
+			info.bustype, bus_str(info.bustype));
+		printf("\tvendor: 0x%04hx\n", info.vendor);
+		printf("\tproduct: 0x%04hx\n", info.product);
+	}
+
+	/* Set Feature */
+	buf[0] = 0x9; /* Report Number */
+	buf[1] = 0xff;
+	buf[2] = 0xff;
+	buf[3] = 0xff;
+	res = ioctl(fd, HIDIOCSFEATURE(4), buf);
+	if (res < 0)
+		perror("HIDIOCSFEATURE");
+	else
+		printf("ioctl HIDIOCSFEATURE returned: %d\n", res);
+
+	/* Get Feature */
+	buf[0] = 0x9; /* Report Number */
+	res = ioctl(fd, HIDIOCGFEATURE(256), buf);
+	if (res < 0) {
+		perror("HIDIOCGFEATURE");
+	} else {
+		printf("ioctl HIDIOCGFEATURE returned: %d\n", res);
+		printf("Report data:\n\t");
+		for (i = 0; i < res; i++)
+			printf("%hhx ", buf[i]);
+		puts("\n");
+	}
+
+	/* Send a Report to the Device */
+	buf[0] = 0x1; /* Report Number */
+	buf[1] = 0x77;
+	res = write(fd, buf, 2);
+	if (res < 0) {
+		printf("Error: %d\n", errno);
+		perror("write");
+	} else {
+		printf("write() wrote %d bytes\n", res);
+	}
+
+	/* Get a report from the device */
+	res = read(fd, buf, 16);
+	if (res < 0) {
+		perror("read");
+	} else {
+		printf("read() read %d bytes:\n\t", res);
+		for (i = 0; i < res; i++)
+			printf("%hhx ", buf[i]);
+		puts("\n");
+	}
+	close(fd);
+	return 0;
+}
+
+const char *
+bus_str(int bus)
+{
+	switch (bus) {
+	case BUS_USB:
+		return "USB";
+		break;
+	case BUS_HIL:
+		return "HIL";
+		break;
+	case BUS_BLUETOOTH:
+		return "Bluetooth";
+		break;
+	case BUS_VIRTUAL:
+		return "Virtual";
+		break;
+	default:
+		return "Other";
+		break;
+	}
+}