ALSA: Avoid using timespec for struct snd_timer_status

struct snd_timer_status uses 'timespec' type variables to record
timestamp, which will be changed to an incompatible layout with
updated user space using 64-bit time_t.

To handle both the old and the new layout on 32-bit architectures,
this patch introduces 'struct snd_timer_status32' and 'struct snd_timer_status64'
to handle 32bit time_t and 64bit time_t in native mode and compat mode,
which replaces timespec with s64 type.

When glibc changes time_t to 64-bit, any recompiled program will issue
ioctl commands that the kernel does not understand without this patch.

In the public uapi header, snd_timer_status is now guarded by
an #ifndef __KERNEL__ to avoid referencing 'struct timespec'.
The timespec definition will be removed from the kernel to prevent
new y2038 bugs and to avoid the conflict with an incompatible libc
type of the same name.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 56 insertions, 6 deletions

diff --git a/sound/core/timer.c b/sound/core/timer.c
index d808d5554c7a..d2f69039f941 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -65,6 +65,30 @@ struct snd_timer_user {
 	struct mutex ioctl_lock;
 };
 
+struct snd_timer_status32 {
+	s32 tstamp_sec;			/* Timestamp - last update */
+	s32 tstamp_nsec;
+	unsigned int resolution;	/* current period resolution in ns */
+	unsigned int lost;		/* counter of master tick lost */
+	unsigned int overrun;		/* count of read queue overruns */
+	unsigned int queue;		/* used queue size */
+	unsigned char reserved[64];	/* reserved */
+};
+
+#define SNDRV_TIMER_IOCTL_STATUS32	_IOR('T', 0x14, struct snd_timer_status32)
+
+struct snd_timer_status64 {
+	s64 tstamp_sec;			/* Timestamp - last update */
+	s64 tstamp_nsec;
+	unsigned int resolution;	/* current period resolution in ns */
+	unsigned int lost;		/* counter of master tick lost */
+	unsigned int overrun;		/* count of read queue overruns */
+	unsigned int queue;		/* used queue size */
+	unsigned char reserved[64];	/* reserved */
+};
+
+#define SNDRV_TIMER_IOCTL_STATUS64	_IOR('T', 0x14, struct snd_timer_status64)
+
 /* list of timers */
 static LIST_HEAD(snd_timer_list);
 
@@ -1875,17 +1899,41 @@ static int snd_timer_user_params(struct file *file,
 	return err;
 }
 
-static int snd_timer_user_status(struct file *file,
-				 struct snd_timer_status __user *_status)
+static int snd_timer_user_status32(struct file *file,
+				   struct snd_timer_status32 __user *_status)
+ {
+	struct snd_timer_user *tu;
+	struct snd_timer_status32 status;
+
+	tu = file->private_data;
+	if (!tu->timeri)
+		return -EBADFD;
+	memset(&status, 0, sizeof(status));
+	status.tstamp_sec = tu->tstamp.tv_sec;
+	status.tstamp_nsec = tu->tstamp.tv_nsec;
+	status.resolution = snd_timer_resolution(tu->timeri);
+	status.lost = tu->timeri->lost;
+	status.overrun = tu->overrun;
+	spin_lock_irq(&tu->qlock);
+	status.queue = tu->qused;
+	spin_unlock_irq(&tu->qlock);
+	if (copy_to_user(_status, &status, sizeof(status)))
+		return -EFAULT;
+	return 0;
+}
+
+static int snd_timer_user_status64(struct file *file,
+				   struct snd_timer_status64 __user *_status)
 {
 	struct snd_timer_user *tu;
-	struct snd_timer_status status;
+	struct snd_timer_status64 status;
 
 	tu = file->private_data;
 	if (!tu->timeri)
 		return -EBADFD;
 	memset(&status, 0, sizeof(status));
-	status.tstamp = timespec64_to_timespec(tu->tstamp);
+	status.tstamp_sec = tu->tstamp.tv_sec;
+	status.tstamp_nsec = tu->tstamp.tv_nsec;
 	status.resolution = snd_timer_resolution(tu->timeri);
 	status.lost = tu->timeri->lost;
 	status.overrun = tu->overrun;
@@ -2009,8 +2057,10 @@ static long __snd_timer_user_ioctl(struct file *file, unsigned int cmd,
 		return snd_timer_user_info(file, argp);
 	case SNDRV_TIMER_IOCTL_PARAMS:
 		return snd_timer_user_params(file, argp);
-	case SNDRV_TIMER_IOCTL_STATUS:
-		return snd_timer_user_status(file, argp);
+	case SNDRV_TIMER_IOCTL_STATUS32:
+		return snd_timer_user_status32(file, argp);
+	case SNDRV_TIMER_IOCTL_STATUS64:
+		return snd_timer_user_status64(file, argp);
 	case SNDRV_TIMER_IOCTL_START:
 	case SNDRV_TIMER_IOCTL_START_OLD:
 		return snd_timer_user_start(file);