1 files changed, 239 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/logger.c b/drivers/md/dm-vdo/logger.c
new file mode 100644
index 000000000000..3f7dc2cb6b98
--- /dev/null
+++ b/drivers/md/dm-vdo/logger.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "logger.h"
+
+#include <asm/current.h>
+#include <linux/delay.h>
+#include <linux/hardirq.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+
+#include "errors.h"
+#include "thread-device.h"
+#include "thread-utils.h"
+
+int vdo_log_level = VDO_LOG_DEFAULT;
+
+int vdo_get_log_level(void)
+{
+	int log_level_latch = READ_ONCE(vdo_log_level);
+
+	if (unlikely(log_level_latch > VDO_LOG_MAX)) {
+		log_level_latch = VDO_LOG_DEFAULT;
+		WRITE_ONCE(vdo_log_level, log_level_latch);
+	}
+	return log_level_latch;
+}
+
+static const char *get_current_interrupt_type(void)
+{
+	if (in_nmi())
+		return "NMI";
+
+	if (in_irq())
+		return "HI";
+
+	if (in_softirq())
+		return "SI";
+
+	return "INTR";
+}
+
+/**
+ * emit_log_message_to_kernel() - Emit a log message to the kernel at the specified priority.
+ *
+ * @priority: The priority at which to log the message
+ * @fmt: The format string of the message
+ */
+static void emit_log_message_to_kernel(int priority, const char *fmt, ...)
+{
+	va_list args;
+	struct va_format vaf;
+
+	if (priority > vdo_get_log_level())
+		return;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	switch (priority) {
+	case VDO_LOG_EMERG:
+	case VDO_LOG_ALERT:
+	case VDO_LOG_CRIT:
+		pr_crit("%pV", &vaf);
+		break;
+	case VDO_LOG_ERR:
+		pr_err("%pV", &vaf);
+		break;
+	case VDO_LOG_WARNING:
+		pr_warn("%pV", &vaf);
+		break;
+	case VDO_LOG_NOTICE:
+	case VDO_LOG_INFO:
+		pr_info("%pV", &vaf);
+		break;
+	case VDO_LOG_DEBUG:
+		pr_debug("%pV", &vaf);
+		break;
+	default:
+		printk(KERN_DEFAULT "%pV", &vaf);
+		break;
+	}
+
+	va_end(args);
+}
+
+/**
+ * emit_log_message() - Emit a log message to the kernel log in a format suited to the current
+ *                      thread context.
+ *
+ * Context info formats:
+ *
+ * interrupt:           uds[NMI]: blah
+ * kvdo thread:         kvdo12:foobarQ: blah
+ * thread w/device id:  kvdo12:myprog: blah
+ * other thread:        uds: myprog: blah
+ *
+ * Fields: module name, interrupt level, process name, device ID.
+ *
+ * @priority: the priority at which to log the message
+ * @module: The name of the module doing the logging
+ * @prefix: The prefix of the log message
+ * @vaf1: The first message format descriptor
+ * @vaf2: The second message format descriptor
+ */
+static void emit_log_message(int priority, const char *module, const char *prefix,
+			     const struct va_format *vaf1, const struct va_format *vaf2)
+{
+	int device_instance;
+
+	/*
+	 * In interrupt context, identify the interrupt type and module. Ignore the process/thread
+	 * since it could be anything.
+	 */
+	if (in_interrupt()) {
+		const char *type = get_current_interrupt_type();
+
+		emit_log_message_to_kernel(priority, "%s[%s]: %s%pV%pV\n", module, type,
+					   prefix, vaf1, vaf2);
+		return;
+	}
+
+	/* Not at interrupt level; we have a process we can look at, and might have a device ID. */
+	device_instance = vdo_get_thread_device_id();
+	if (device_instance >= 0) {
+		emit_log_message_to_kernel(priority, "%s%u:%s: %s%pV%pV\n", module,
+					   device_instance, current->comm, prefix, vaf1,
+					   vaf2);
+		return;
+	}
+
+	/*
+	 * If it's a kernel thread and the module name is a prefix of its name, assume it is ours
+	 * and only identify the thread.
+	 */
+	if (((current->flags & PF_KTHREAD) != 0) &&
+	    (strncmp(module, current->comm, strlen(module)) == 0)) {
+		emit_log_message_to_kernel(priority, "%s: %s%pV%pV\n", current->comm,
+					   prefix, vaf1, vaf2);
+		return;
+	}
+
+	/* Identify the module and the process. */
+	emit_log_message_to_kernel(priority, "%s: %s: %s%pV%pV\n", module, current->comm,
+				   prefix, vaf1, vaf2);
+}
+
+/*
+ * vdo_log_embedded_message() - Log a message embedded within another message.
+ * @priority: the priority at which to log the message
+ * @module: the name of the module doing the logging
+ * @prefix: optional string prefix to message, may be NULL
+ * @fmt1: format of message first part (required)
+ * @args1: arguments for message first part (required)
+ * @fmt2: format of message second part
+ */
+void vdo_log_embedded_message(int priority, const char *module, const char *prefix,
+			      const char *fmt1, va_list args1, const char *fmt2, ...)
+{
+	va_list args1_copy;
+	va_list args2;
+	struct va_format vaf1, vaf2;
+
+	va_start(args2, fmt2);
+
+	if (module == NULL)
+		module = VDO_LOGGING_MODULE_NAME;
+
+	if (prefix == NULL)
+		prefix = "";
+
+	/*
+	 * It is implementation dependent whether va_list is defined as an array type that decays
+	 * to a pointer when passed as an argument. Copy args1 and args2 with va_copy so that vaf1
+	 * and vaf2 get proper va_list pointers irrespective of how va_list is defined.
+	 */
+	va_copy(args1_copy, args1);
+	vaf1.fmt = fmt1;
+	vaf1.va = &args1_copy;
+
+	vaf2.fmt = fmt2;
+	vaf2.va = &args2;
+
+	emit_log_message(priority, module, prefix, &vaf1, &vaf2);
+
+	va_end(args1_copy);
+	va_end(args2);
+}
+
+int vdo_vlog_strerror(int priority, int errnum, const char *module, const char *format,
+		      va_list args)
+{
+	char errbuf[VDO_MAX_ERROR_MESSAGE_SIZE];
+	const char *message = uds_string_error(errnum, errbuf, sizeof(errbuf));
+
+	vdo_log_embedded_message(priority, module, NULL, format, args, ": %s (%d)",
+				 message, errnum);
+	return errnum;
+}
+
+int __vdo_log_strerror(int priority, int errnum, const char *module, const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vdo_vlog_strerror(priority, errnum, module, format, args);
+	va_end(args);
+	return errnum;
+}
+
+void vdo_log_backtrace(int priority)
+{
+	if (priority > vdo_get_log_level())
+		return;
+
+	dump_stack();
+}
+
+void __vdo_log_message(int priority, const char *module, const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vdo_log_embedded_message(priority, module, NULL, format, args, "%s", "");
+	va_end(args);
+}
+
+/*
+ * Sleep or delay a few milliseconds in an attempt to allow the log buffers to be flushed lest they
+ * be overrun.
+ */
+void vdo_pause_for_logger(void)
+{
+	fsleep(4000);
+}