iio: proximity: isl29501: Fix return type of isl29501_register_writegrafted

isl29501_register_write() was returning a u32 instead of an int.
Since the function returns negative error codes (such as -ERANGE or
return values from i2c_smbus_write_byte_data()), returning an unsigned
integer type prevents callers from correctly checking for negative error
conditions.

Fix this by changing the function return type from u32 to int.

This was found through manual code review.

Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 139 insertions, 0 deletions

diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
new file mode 100644
index 000000000..f39c9eca8
--- /dev/null
+++ b/lib/nmi_backtrace.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  NMI backtrace support
+ *
+ * Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King,
+ * with the following header:
+ *
+ *  HW NMI watchdog support
+ *
+ *  started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
+ *
+ *  Arch specific calls to support NMI watchdog
+ *
+ *  Bits copied from original nmi.c file
+ */
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+#include <linux/kprobes.h>
+#include <linux/stringify.h>
+#include <linux/nmi.h>
+#include <linux/cpu.h>
+#include <linux/export.h>
+#include <linux/sched/debug.h>
+
+#ifdef arch_trigger_cpumask_backtrace
+/* For reliability, we're prepared to waste bits here. */
+static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
+
+/* "in progress" flag of arch_trigger_cpumask_backtrace */
+static unsigned long backtrace_flag;
+
+#define NMI_BT_TIMEOUT_SEC	10
+
+/*
+ * When raise() is called it will be passed a pointer to the
+ * backtrace_mask. Architectures that call nmi_cpu_backtrace()
+ * directly from their raise() functions may rely on the mask
+ * they are passed being updated as a side effect of this call.
+ */
+void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
+				   int exclude_cpu,
+				   void (*raise)(cpumask_t *mask))
+{
+	int i, this_cpu = get_cpu();
+
+	if (test_and_set_bit(0, &backtrace_flag)) {
+		/*
+		 * If there is already a trigger_all_cpu_backtrace() in progress
+		 * (backtrace_flag == 1), don't output double cpu dump infos.
+		 */
+		put_cpu();
+		return;
+	}
+
+	cpumask_copy(to_cpumask(backtrace_mask), mask);
+	if (exclude_cpu != -1)
+		cpumask_clear_cpu(exclude_cpu, to_cpumask(backtrace_mask));
+
+	/*
+	 * Don't try to send an NMI to this cpu; it may work on some
+	 * architectures, but on others it may not, and we'll get
+	 * information at least as useful just by doing a dump_stack() here.
+	 * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit.
+	 */
+	if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask)))
+		nmi_cpu_backtrace(NULL);
+
+	if (!cpumask_empty(to_cpumask(backtrace_mask))) {
+		pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n",
+			this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask));
+		nmi_backtrace_stall_snap(to_cpumask(backtrace_mask));
+		raise(to_cpumask(backtrace_mask));
+	}
+
+	/* Wait for up to NMI_BT_TIMEOUT_SEC seconds for all CPUs to do the backtrace */
+	for (i = 0; i < NMI_BT_TIMEOUT_SEC * 1000; i++) {
+		if (cpumask_empty(to_cpumask(backtrace_mask)))
+			break;
+		mdelay(1);
+		touch_softlockup_watchdog();
+	}
+
+	if (!cpumask_empty(to_cpumask(backtrace_mask))) {
+		pr_warn("After " __stringify(NMI_BT_TIMEOUT_SEC) " seconds, these CPUS still haven't responded to the NMI: %*pbl\n",
+			cpumask_pr_args(to_cpumask(backtrace_mask)));
+
+		nmi_backtrace_stall_check(to_cpumask(backtrace_mask));
+	}
+
+	/*
+	 * Force flush any remote buffers that might be stuck in IRQ context
+	 * and therefore could not run their irq_work.
+	 */
+	printk_trigger_flush();
+
+	clear_bit_unlock(0, &backtrace_flag);
+	put_cpu();
+}
+
+// Dump stacks even for idle CPUs.
+static bool backtrace_idle;
+module_param(backtrace_idle, bool, 0644);
+
+bool nmi_cpu_backtrace(struct pt_regs *regs)
+{
+	int cpu = smp_processor_id();
+	unsigned long flags;
+
+	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
+		/*
+		 * Allow nested NMI backtraces while serializing
+		 * against other CPUs.
+		 */
+		printk_cpu_sync_get_irqsave(flags);
+		if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) {
+			pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n",
+				cpu, (void *)instruction_pointer(regs));
+		} else {
+			pr_warn("NMI backtrace for cpu %d\n", cpu);
+			if (regs)
+				show_regs(regs);
+			else
+				dump_stack();
+		}
+		printk_cpu_sync_put_irqrestore(flags);
+		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
+		return true;
+	}
+
+	return false;
+}
+NOKPROBE_SYMBOL(nmi_cpu_backtrace);
+
+void cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
+{
+	arch_trigger_cpumask_backtrace(mask, exclude_cpu);
+}
+EXPORT_SYMBOL_GPL(cpumask_backtrace);
+#endif