staging: android: logger: Allocate logs dynamically at boot (v3)

This changes the log initialization to be dynamic, but still
at boot time.  These changes are a predecessor to implementing
runtime allocation and freeing of logs, to make the Android logger
less hard-coded.

Change from a fixed set of static log structures, to allocation
at init time into a list.  Return proper error numbers on log
allocation failure.

Cc: Brian Swetland <swetland@google.com>
Signed-off-by: NTim Bird <tim.bird@am.sony.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/logger.c

@@ -25,6 +25,7 @@
 #include <linux/poll.h>
 #include <linux/slab.h>
 #include <linux/time.h>
+#include <linux/vmalloc.h>
 #include "logger.h"
 
 #include <asm/ioctls.h>
@@ -45,8 +46,12 @@ struct logger_log {
 	size_t			w_off;	/* current write head offset */
 	size_t			head;	/* new readers start here */
 	size_t			size;	/* size of the log */
+	struct list_head	logs;	/* list of log channels (myself)*/
 };
 
+static LIST_HEAD(log_list);
+
+
 /*
  * struct logger_reader - a logging device open for reading
  *
@@ -408,7 +413,15 @@ ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	return ret;
 }
 
-static struct logger_log *get_log_from_minor(int);
+static struct logger_log *get_log_from_minor(int minor)
+{
+	struct logger_log *log;
+
+	list_for_each_entry(log, &log_list, logs)
+		if (log->misc.minor == minor)
+			return log;
+	return NULL;
+}
 
 /*
  * logger_open - the log's open() file operation
@@ -565,80 +578,84 @@ static const struct file_operations logger_fops = {
 };
 
 /*
- * Defines a log structure with name 'NAME' and a size of 'SIZE' bytes, which
- * must be a power of two, greater than LOGGER_ENTRY_MAX_LEN, and less than
- * LONG_MAX minus LOGGER_ENTRY_MAX_LEN.
+ * Log size must be a power of two, greater than LOGGER_ENTRY_MAX_LEN,
+ * and less than LONG_MAX minus LOGGER_ENTRY_MAX_LEN.
  */
-#define DEFINE_LOGGER_DEVICE(VAR, NAME, SIZE) \
-static unsigned char _buf_ ## VAR[SIZE]; \
-static struct logger_log VAR = { \
-	.buffer = _buf_ ## VAR, \
-	.misc = { \
-		.minor = MISC_DYNAMIC_MINOR, \
-		.name = NAME, \
-		.fops = &logger_fops, \
-		.parent = NULL, \
-	}, \
-	.wq = __WAIT_QUEUE_HEAD_INITIALIZER(VAR .wq), \
-	.readers = LIST_HEAD_INIT(VAR .readers), \
-	.mutex = __MUTEX_INITIALIZER(VAR .mutex), \
-	.w_off = 0, \
-	.head = 0, \
-	.size = SIZE, \
-};
+static int __init create_log(char *log_name, int size)
+{
+	int ret = 0;
+	struct logger_log *log;
+	unsigned char *buffer;
 
-DEFINE_LOGGER_DEVICE(log_main, LOGGER_LOG_MAIN, 256*1024)
-DEFINE_LOGGER_DEVICE(log_events, LOGGER_LOG_EVENTS, 256*1024)
-DEFINE_LOGGER_DEVICE(log_radio, LOGGER_LOG_RADIO, 256*1024)
-DEFINE_LOGGER_DEVICE(log_system, LOGGER_LOG_SYSTEM, 256*1024)
+	buffer = vmalloc(size);
+	if (buffer == NULL)
+		return -ENOMEM;
 
-static struct logger_log *get_log_from_minor(int minor)
-{
-	if (log_main.misc.minor == minor)
-		return &log_main;
-	if (log_events.misc.minor == minor)
-		return &log_events;
-	if (log_radio.misc.minor == minor)
-		return &log_radio;
-	if (log_system.misc.minor == minor)
-		return &log_system;
-	return NULL;
-}
+	log = kzalloc(sizeof(struct logger_log), GFP_KERNEL);
+	if (log == NULL) {
+		ret = -ENOMEM;
+		goto out_free_buffer;
+	}
+	log->buffer = buffer;
 
-static int __init init_log(struct logger_log *log)
-{
-	int ret;
+	log->misc.minor = MISC_DYNAMIC_MINOR;
+	log->misc.name = kstrdup(log_name, GFP_KERNEL);
+	if (log->misc.name == NULL) {
+		ret = -ENOMEM;
+		goto out_free_log;
+	}
+
+	log->misc.fops = &logger_fops;
+	log->misc.parent = NULL;
 
+	init_waitqueue_head(&log->wq);
+	INIT_LIST_HEAD(&log->readers);
+	mutex_init(&log->mutex);
+	log->w_off = 0;
+	log->head = 0;
+	log->size = size;
+
+	INIT_LIST_HEAD(&log->logs);
+	list_add_tail(&log->logs, &log_list);
+
+	/* finally, initialize the misc device for this log */
 	ret = misc_register(&log->misc);
 	if (unlikely(ret)) {
 		printk(KERN_ERR "logger: failed to register misc "
 		       "device for log '%s'!\n", log->misc.name);
-		return ret;
+		goto out_free_log;
 	}
 
 	printk(KERN_INFO "logger: created %luK log '%s'\n",
 	       (unsigned long) log->size >> 10, log->misc.name);
 
 	return 0;
+
+out_free_log:
+	kfree(log);
+
+out_free_buffer:
+	vfree(buffer);
+	return ret;
 }
 
 static int __init logger_init(void)
 {
 	int ret;
 
-	ret = init_log(&log_main);
+	ret = create_log(LOGGER_LOG_MAIN, 256*1024);
 	if (unlikely(ret))
 		goto out;
 
-	ret = init_log(&log_events);
+	ret = create_log(LOGGER_LOG_EVENTS, 256*1024);
 	if (unlikely(ret))
 		goto out;
 
-	ret = init_log(&log_radio);
+	ret = create_log(LOGGER_LOG_RADIO, 256*1024);
 	if (unlikely(ret))
 		goto out;
 
-	ret = init_log(&log_system);
+	ret = create_log(LOGGER_LOG_SYSTEM, 256*1024);
 	if (unlikely(ret))
 		goto out;