The previous patch introduced the internal infrastructure for handling
64-bit timestamps. This patch exposes this capability to user-space.
Define the new ioctl command SNDRV_COMPRESS_TSTAMP64, which allows
applications to fetch the overflow-safe struct snd_compr_tstamp64.
The ioctl dispatch table is updated to handle the new command by
calling a new snd_compr_tstamp64 handler, while the legacy path is
renamed to snd_compr_tstamp32 for clarity.
This patch bumps the SNDRV_COMPRESS_VERSION to 0.4.0.
Reviewed-by: Miller Liang <millerliang@google.com>
Tested-by: Joris Verhaegen <verhaegen@google.com>
Signed-off-by: Joris Verhaegen <verhaegen@google.com>
---
include/uapi/sound/compress_offload.h | 5 +++--
sound/core/compress_offload.c | 19 +++++++++++++------
2 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
index abd0ea3f86ee..70b8921601f9 100644
--- a/include/uapi/sound/compress_offload.h
+++ b/include/uapi/sound/compress_offload.h
@@ -13,8 +13,7 @@
#include <sound/asound.h>
#include <sound/compress_params.h>
-
-#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0)
+#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 4, 0)
/**
* struct snd_compressed_buffer - compressed buffer
* @fragment_size: size of buffer fragment in bytes
@@ -208,6 +207,7 @@ struct snd_compr_task_status {
* Note: only codec params can be changed runtime and stream params cant be
* SNDRV_COMPRESS_GET_PARAMS: Query codec params
* SNDRV_COMPRESS_TSTAMP: get the current timestamp value
+ * SNDRV_COMPRESS_TSTAMP64: get the current timestamp value in 64 bit format
* SNDRV_COMPRESS_AVAIL: get the current buffer avail value.
* This also queries the tstamp properties
* SNDRV_COMPRESS_PAUSE: Pause the running stream
@@ -230,6 +230,7 @@ struct snd_compr_task_status {
struct snd_compr_metadata)
#define SNDRV_COMPRESS_TSTAMP _IOR('C', 0x20, struct snd_compr_tstamp)
#define SNDRV_COMPRESS_AVAIL _IOR('C', 0x21, struct snd_compr_avail)
+#define SNDRV_COMPRESS_TSTAMP64 _IOR('C', 0x22, struct snd_compr_tstamp64)
#define SNDRV_COMPRESS_PAUSE _IO('C', 0x30)
#define SNDRV_COMPRESS_RESUME _IO('C', 0x31)
#define SNDRV_COMPRESS_START _IO('C', 0x32)
diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index d3164aa07158..445220fdb6a0 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -736,18 +736,23 @@ snd_compr_set_metadata(struct snd_compr_stream *stream, unsigned long arg)
return retval;
}
-static inline int
-snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg)
+static inline int snd_compr_tstamp(struct snd_compr_stream *stream,
+ unsigned long arg, bool is_32bit)
{
struct snd_compr_tstamp64 tstamp64 = { 0 };
struct snd_compr_tstamp tstamp32 = { 0 };
+ const void *copy_from = &tstamp64;
+ size_t copy_size = sizeof(tstamp64);
int ret;
ret = snd_compr_update_tstamp(stream, &tstamp64);
if (ret == 0) {
- snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
- ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
- &tstamp32, sizeof(tstamp32)) ?
+ if (is_32bit) {
+ snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
+ copy_from = &tstamp32;
+ copy_size = sizeof(tstamp32);
+ }
+ ret = copy_to_user((void __user *)arg, copy_from, copy_size) ?
-EFAULT :
0;
}
@@ -1327,7 +1332,9 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
switch (cmd) {
case SNDRV_COMPRESS_TSTAMP:
- return snd_compr_tstamp(stream, arg);
+ return snd_compr_tstamp(stream, arg, true);
+ case SNDRV_COMPRESS_TSTAMP64:
+ return snd_compr_tstamp(stream, arg, false);
case SNDRV_COMPRESS_AVAIL:
return snd_compr_ioctl_avail(stream, arg);
case SNDRV_COMPRESS_PAUSE:
--
2.50.1.565.gc32cd1483b-googOn 01-08-25, 10:27, Joris Verhaegen wrote:
> The previous patch introduced the internal infrastructure for handling
> 64-bit timestamps. This patch exposes this capability to user-space.
>
> Define the new ioctl command SNDRV_COMPRESS_TSTAMP64, which allows
> applications to fetch the overflow-safe struct snd_compr_tstamp64.
>
> The ioctl dispatch table is updated to handle the new command by
> calling a new snd_compr_tstamp64 handler, while the legacy path is
> renamed to snd_compr_tstamp32 for clarity.
>
> This patch bumps the SNDRV_COMPRESS_VERSION to 0.4.0.
>
> Reviewed-by: Miller Liang <millerliang@google.com>
> Tested-by: Joris Verhaegen <verhaegen@google.com>
> Signed-off-by: Joris Verhaegen <verhaegen@google.com>
> ---
> include/uapi/sound/compress_offload.h | 5 +++--
> sound/core/compress_offload.c | 19 +++++++++++++------
> 2 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
> index abd0ea3f86ee..70b8921601f9 100644
> --- a/include/uapi/sound/compress_offload.h
> +++ b/include/uapi/sound/compress_offload.h
> @@ -13,8 +13,7 @@
> #include <sound/asound.h>
> #include <sound/compress_params.h>
>
> -
> -#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0)
> +#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 4, 0)
> /**
> * struct snd_compressed_buffer - compressed buffer
> * @fragment_size: size of buffer fragment in bytes
> @@ -208,6 +207,7 @@ struct snd_compr_task_status {
> * Note: only codec params can be changed runtime and stream params cant be
> * SNDRV_COMPRESS_GET_PARAMS: Query codec params
> * SNDRV_COMPRESS_TSTAMP: get the current timestamp value
> + * SNDRV_COMPRESS_TSTAMP64: get the current timestamp value in 64 bit format
> * SNDRV_COMPRESS_AVAIL: get the current buffer avail value.
> * This also queries the tstamp properties
> * SNDRV_COMPRESS_PAUSE: Pause the running stream
> @@ -230,6 +230,7 @@ struct snd_compr_task_status {
> struct snd_compr_metadata)
> #define SNDRV_COMPRESS_TSTAMP _IOR('C', 0x20, struct snd_compr_tstamp)
> #define SNDRV_COMPRESS_AVAIL _IOR('C', 0x21, struct snd_compr_avail)
> +#define SNDRV_COMPRESS_TSTAMP64 _IOR('C', 0x22, struct snd_compr_tstamp64)
> #define SNDRV_COMPRESS_PAUSE _IO('C', 0x30)
> #define SNDRV_COMPRESS_RESUME _IO('C', 0x31)
> #define SNDRV_COMPRESS_START _IO('C', 0x32)
> diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
> index d3164aa07158..445220fdb6a0 100644
> --- a/sound/core/compress_offload.c
> +++ b/sound/core/compress_offload.c
> @@ -736,18 +736,23 @@ snd_compr_set_metadata(struct snd_compr_stream *stream, unsigned long arg)
> return retval;
> }
>
> -static inline int
> -snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg)
> +static inline int snd_compr_tstamp(struct snd_compr_stream *stream,
> + unsigned long arg, bool is_32bit)
> {
> struct snd_compr_tstamp64 tstamp64 = { 0 };
> struct snd_compr_tstamp tstamp32 = { 0 };
> + const void *copy_from = &tstamp64;
> + size_t copy_size = sizeof(tstamp64);
> int ret;
>
> ret = snd_compr_update_tstamp(stream, &tstamp64);
> if (ret == 0) {
> - snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> - ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
> - &tstamp32, sizeof(tstamp32)) ?
> + if (is_32bit) {
> + snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> + copy_from = &tstamp32;
> + copy_size = sizeof(tstamp32);
> + }
Most of the applications and people would be 32bit right now and we
expect this to progressively change, but then this imposes a penalty as
default path is 64 bit, since we expect this ioctl to be called very
frequently, should we do this optimization for 64bit here?
> + ret = copy_to_user((void __user *)arg, copy_from, copy_size) ?
> -EFAULT :
> 0;
> }
> @@ -1327,7 +1332,9 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
>
> switch (cmd) {
> case SNDRV_COMPRESS_TSTAMP:
> - return snd_compr_tstamp(stream, arg);
> + return snd_compr_tstamp(stream, arg, true);
> + case SNDRV_COMPRESS_TSTAMP64:
> + return snd_compr_tstamp(stream, arg, false);
> case SNDRV_COMPRESS_AVAIL:
> return snd_compr_ioctl_avail(stream, arg);
> case SNDRV_COMPRESS_PAUSE:
> --
> 2.50.1.565.gc32cd1483b-goog
--
~Vinod
On Tue, 05 Aug 2025 06:47:59 +0200,
Vinod Koul wrote:
>
> On 01-08-25, 10:27, Joris Verhaegen wrote:
> > The previous patch introduced the internal infrastructure for handling
> > 64-bit timestamps. This patch exposes this capability to user-space.
> >
> > Define the new ioctl command SNDRV_COMPRESS_TSTAMP64, which allows
> > applications to fetch the overflow-safe struct snd_compr_tstamp64.
> >
> > The ioctl dispatch table is updated to handle the new command by
> > calling a new snd_compr_tstamp64 handler, while the legacy path is
> > renamed to snd_compr_tstamp32 for clarity.
> >
> > This patch bumps the SNDRV_COMPRESS_VERSION to 0.4.0.
> >
> > Reviewed-by: Miller Liang <millerliang@google.com>
> > Tested-by: Joris Verhaegen <verhaegen@google.com>
> > Signed-off-by: Joris Verhaegen <verhaegen@google.com>
> > ---
> > include/uapi/sound/compress_offload.h | 5 +++--
> > sound/core/compress_offload.c | 19 +++++++++++++------
> > 2 files changed, 16 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
> > index abd0ea3f86ee..70b8921601f9 100644
> > --- a/include/uapi/sound/compress_offload.h
> > +++ b/include/uapi/sound/compress_offload.h
> > @@ -13,8 +13,7 @@
> > #include <sound/asound.h>
> > #include <sound/compress_params.h>
> >
> > -
> > -#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0)
> > +#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 4, 0)
> > /**
> > * struct snd_compressed_buffer - compressed buffer
> > * @fragment_size: size of buffer fragment in bytes
> > @@ -208,6 +207,7 @@ struct snd_compr_task_status {
> > * Note: only codec params can be changed runtime and stream params cant be
> > * SNDRV_COMPRESS_GET_PARAMS: Query codec params
> > * SNDRV_COMPRESS_TSTAMP: get the current timestamp value
> > + * SNDRV_COMPRESS_TSTAMP64: get the current timestamp value in 64 bit format
> > * SNDRV_COMPRESS_AVAIL: get the current buffer avail value.
> > * This also queries the tstamp properties
> > * SNDRV_COMPRESS_PAUSE: Pause the running stream
> > @@ -230,6 +230,7 @@ struct snd_compr_task_status {
> > struct snd_compr_metadata)
> > #define SNDRV_COMPRESS_TSTAMP _IOR('C', 0x20, struct snd_compr_tstamp)
> > #define SNDRV_COMPRESS_AVAIL _IOR('C', 0x21, struct snd_compr_avail)
> > +#define SNDRV_COMPRESS_TSTAMP64 _IOR('C', 0x22, struct snd_compr_tstamp64)
> > #define SNDRV_COMPRESS_PAUSE _IO('C', 0x30)
> > #define SNDRV_COMPRESS_RESUME _IO('C', 0x31)
> > #define SNDRV_COMPRESS_START _IO('C', 0x32)
> > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
> > index d3164aa07158..445220fdb6a0 100644
> > --- a/sound/core/compress_offload.c
> > +++ b/sound/core/compress_offload.c
> > @@ -736,18 +736,23 @@ snd_compr_set_metadata(struct snd_compr_stream *stream, unsigned long arg)
> > return retval;
> > }
> >
> > -static inline int
> > -snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg)
> > +static inline int snd_compr_tstamp(struct snd_compr_stream *stream,
> > + unsigned long arg, bool is_32bit)
> > {
> > struct snd_compr_tstamp64 tstamp64 = { 0 };
> > struct snd_compr_tstamp tstamp32 = { 0 };
> > + const void *copy_from = &tstamp64;
> > + size_t copy_size = sizeof(tstamp64);
> > int ret;
> >
> > ret = snd_compr_update_tstamp(stream, &tstamp64);
> > if (ret == 0) {
> > - snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > - ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
> > - &tstamp32, sizeof(tstamp32)) ?
> > + if (is_32bit) {
> > + snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > + copy_from = &tstamp32;
> > + copy_size = sizeof(tstamp32);
> > + }
>
> Most of the applications and people would be 32bit right now and we
> expect this to progressively change, but then this imposes a penalty as
> default path is 64 bit, since we expect this ioctl to be called very
> frequently, should we do this optimization for 64bit here?
Through a quick glance over the patch, I don't think you'll hit the
significant performance loss. It's merely a few bytes of extra copies
before copy_to_user(), after all. But, of course, it'd be more
convincing if anyone can test and give the actual numbers.
thanks,
Takashi
On Tue, Aug 05, 2025 at 07:59:42AM +0200, Takashi Iwai wrote:
> On Tue, 05 Aug 2025 06:47:59 +0200,
> Vinod Koul wrote:
> > On 01-08-25, 10:27, Joris Verhaegen wrote:
> > > ret = snd_compr_update_tstamp(stream, &tstamp64);
> > > if (ret == 0) {
> > > - snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > > - ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
> > > - &tstamp32, sizeof(tstamp32)) ?
> > > + if (is_32bit) {
> > > + snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > > + copy_from = &tstamp32;
> > > + copy_size = sizeof(tstamp32);
> > > + }
> >
> > Most of the applications and people would be 32bit right now and we
> > expect this to progressively change, but then this imposes a penalty as
> > default path is 64 bit, since we expect this ioctl to be called very
> > frequently, should we do this optimization for 64bit here?
>
> Through a quick glance over the patch, I don't think you'll hit the
> significant performance loss. It's merely a few bytes of extra copies
> before copy_to_user(), after all. But, of course, it'd be more
> convincing if anyone can test and give the actual numbers.
>
I am inclined to agree the impact should be very minimal and the
only alternative is a more complex implementation. I would vote
for leaving this as is.
Thanks,
Charles
On 18-08-25, 15:05, Charles Keepax wrote:
> On Tue, Aug 05, 2025 at 07:59:42AM +0200, Takashi Iwai wrote:
> > On Tue, 05 Aug 2025 06:47:59 +0200,
> > Vinod Koul wrote:
> > > On 01-08-25, 10:27, Joris Verhaegen wrote:
> > > > ret = snd_compr_update_tstamp(stream, &tstamp64);
> > > > if (ret == 0) {
> > > > - snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > > > - ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
> > > > - &tstamp32, sizeof(tstamp32)) ?
> > > > + if (is_32bit) {
> > > > + snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > > > + copy_from = &tstamp32;
> > > > + copy_size = sizeof(tstamp32);
> > > > + }
> > >
> > > Most of the applications and people would be 32bit right now and we
> > > expect this to progressively change, but then this imposes a penalty as
> > > default path is 64 bit, since we expect this ioctl to be called very
> > > frequently, should we do this optimization for 64bit here?
> >
> > Through a quick glance over the patch, I don't think you'll hit the
> > significant performance loss. It's merely a few bytes of extra copies
> > before copy_to_user(), after all. But, of course, it'd be more
> > convincing if anyone can test and give the actual numbers.
That would be better
> I am inclined to agree the impact should be very minimal and the
> only alternative is a more complex implementation. I would vote
> for leaving this as is.
But yes, we can for now, go ahead. It is internal kernel flow can be
adapted anytime :-)
--
~Vinod
On Tue, 19 Aug 2025 07:08:08 +0200,
Vinod Koul wrote:
>
> On 18-08-25, 15:05, Charles Keepax wrote:
> > On Tue, Aug 05, 2025 at 07:59:42AM +0200, Takashi Iwai wrote:
> > > On Tue, 05 Aug 2025 06:47:59 +0200,
> > > Vinod Koul wrote:
> > > > On 01-08-25, 10:27, Joris Verhaegen wrote:
> > > > > ret = snd_compr_update_tstamp(stream, &tstamp64);
> > > > > if (ret == 0) {
> > > > > - snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > > > > - ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
> > > > > - &tstamp32, sizeof(tstamp32)) ?
> > > > > + if (is_32bit) {
> > > > > + snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > > > > + copy_from = &tstamp32;
> > > > > + copy_size = sizeof(tstamp32);
> > > > > + }
> > > >
> > > > Most of the applications and people would be 32bit right now and we
> > > > expect this to progressively change, but then this imposes a penalty as
> > > > default path is 64 bit, since we expect this ioctl to be called very
> > > > frequently, should we do this optimization for 64bit here?
> > >
> > > Through a quick glance over the patch, I don't think you'll hit the
> > > significant performance loss. It's merely a few bytes of extra copies
> > > before copy_to_user(), after all. But, of course, it'd be more
> > > convincing if anyone can test and give the actual numbers.
>
> That would be better
>
> > I am inclined to agree the impact should be very minimal and the
> > only alternative is a more complex implementation. I would vote
> > for leaving this as is.
>
> But yes, we can for now, go ahead. It is internal kernel flow can be
> adapted anytime :-)
OK, Joris, could you submit v5 with correction of what Vinod
suggested in reviews?
thanks,
Takashi
On Thu, 21 Aug 2025 at 08:18, Takashi Iwai <tiwai@suse.de> wrote: > OK, Joris, could you submit v5 with correction of what Vinod > suggested in reviews? Submitted v5 with revert of the alignment change. I think that was the only remaining open item. Thanks, George (Joris)
On Tue, 05 Aug 2025 06:47:59 +0200,
Vinod Koul wrote:
>
> On 01-08-25, 10:27, Joris Verhaegen wrote:
> > The previous patch introduced the internal infrastructure for handling
> > 64-bit timestamps. This patch exposes this capability to user-space.
> >
> > Define the new ioctl command SNDRV_COMPRESS_TSTAMP64, which allows
> > applications to fetch the overflow-safe struct snd_compr_tstamp64.
> >
> > The ioctl dispatch table is updated to handle the new command by
> > calling a new snd_compr_tstamp64 handler, while the legacy path is
> > renamed to snd_compr_tstamp32 for clarity.
> >
> > This patch bumps the SNDRV_COMPRESS_VERSION to 0.4.0.
> >
> > Reviewed-by: Miller Liang <millerliang@google.com>
> > Tested-by: Joris Verhaegen <verhaegen@google.com>
> > Signed-off-by: Joris Verhaegen <verhaegen@google.com>
> > ---
> > include/uapi/sound/compress_offload.h | 5 +++--
> > sound/core/compress_offload.c | 19 +++++++++++++------
> > 2 files changed, 16 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h
> > index abd0ea3f86ee..70b8921601f9 100644
> > --- a/include/uapi/sound/compress_offload.h
> > +++ b/include/uapi/sound/compress_offload.h
> > @@ -13,8 +13,7 @@
> > #include <sound/asound.h>
> > #include <sound/compress_params.h>
> >
> > -
> > -#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0)
> > +#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 4, 0)
> > /**
> > * struct snd_compressed_buffer - compressed buffer
> > * @fragment_size: size of buffer fragment in bytes
> > @@ -208,6 +207,7 @@ struct snd_compr_task_status {
> > * Note: only codec params can be changed runtime and stream params cant be
> > * SNDRV_COMPRESS_GET_PARAMS: Query codec params
> > * SNDRV_COMPRESS_TSTAMP: get the current timestamp value
> > + * SNDRV_COMPRESS_TSTAMP64: get the current timestamp value in 64 bit format
> > * SNDRV_COMPRESS_AVAIL: get the current buffer avail value.
> > * This also queries the tstamp properties
> > * SNDRV_COMPRESS_PAUSE: Pause the running stream
> > @@ -230,6 +230,7 @@ struct snd_compr_task_status {
> > struct snd_compr_metadata)
> > #define SNDRV_COMPRESS_TSTAMP _IOR('C', 0x20, struct snd_compr_tstamp)
> > #define SNDRV_COMPRESS_AVAIL _IOR('C', 0x21, struct snd_compr_avail)
> > +#define SNDRV_COMPRESS_TSTAMP64 _IOR('C', 0x22, struct snd_compr_tstamp64)
> > #define SNDRV_COMPRESS_PAUSE _IO('C', 0x30)
> > #define SNDRV_COMPRESS_RESUME _IO('C', 0x31)
> > #define SNDRV_COMPRESS_START _IO('C', 0x32)
> > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
> > index d3164aa07158..445220fdb6a0 100644
> > --- a/sound/core/compress_offload.c
> > +++ b/sound/core/compress_offload.c
> > @@ -736,18 +736,23 @@ snd_compr_set_metadata(struct snd_compr_stream *stream, unsigned long arg)
> > return retval;
> > }
> >
> > -static inline int
> > -snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg)
> > +static inline int snd_compr_tstamp(struct snd_compr_stream *stream,
> > + unsigned long arg, bool is_32bit)
> > {
> > struct snd_compr_tstamp64 tstamp64 = { 0 };
> > struct snd_compr_tstamp tstamp32 = { 0 };
> > + const void *copy_from = &tstamp64;
> > + size_t copy_size = sizeof(tstamp64);
> > int ret;
> >
> > ret = snd_compr_update_tstamp(stream, &tstamp64);
> > if (ret == 0) {
> > - snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > - ret = copy_to_user((struct snd_compr_tstamp __user *)arg,
> > - &tstamp32, sizeof(tstamp32)) ?
> > + if (is_32bit) {
> > + snd_compr_tstamp32_from_64(&tstamp32, &tstamp64);
> > + copy_from = &tstamp32;
> > + copy_size = sizeof(tstamp32);
> > + }
>
> Most of the applications and people would be 32bit right now and we
> expect this to progressively change, but then this imposes a penalty as
> default path is 64 bit, since we expect this ioctl to be called very
> frequently, should we do this optimization for 64bit here?
Valid point about optimizing the common path. But since the underlying
.pointer op was changed in the patch V3 to always return a 64-bit
snd_compr_tstamp64, there is no longer a "native" 32-bit path to fetch.
Any call to the legacy SNDRV_COMPRESS_TSTAMP ioctl must fetch the 64-bit
value and then truncate it down. The current patch reflects this by sharing the
common 64-bit fetch and then conditionally performing the truncation to 32-bit.
Splitting the function would result in two functions that both call
snd_compr_update_tstamp() to get the 64-bit data, so there would be code
duplication with no performance gain.
Thanks,
George
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