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relay: Use per CPU constructs for the relay channel buffer pointers

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relay essentially needs to maintain a per CPU array of channel buffer
pointers but it manually creates that array.  Instead its better to use
the per CPU constructs, provided by the kernel, to allocate & access the
array of pointer to channel buffers.

Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://lkml.kernel.org/r/1470909140-25919-1-git-send-email-akash.goel@intel.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Akash Goel 2016-09-02 21:47:38 +02:00 • committed by Thomas Gleixner
parent ee1e714b94
commit 017c59c042
2 changed files with 52 additions and 39 deletions
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17
include/linux/relay.h
View file

@ -19,6 +19,7 @@
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/kref.h>
#include <linux/percpu.h>
/*
* Tracks changes to rchan/rchan_buf structs
@ -63,7 +64,7 @@ struct rchan
struct kref kref; /* channel refcount */
void *private_data; /* for user-defined data */
size_t last_toobig; /* tried to log event > subbuf size */
struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */
struct rchan_buf ** __percpu buf; /* per-cpu channel buffers */
int is_global; /* One global buffer ? */
struct list_head list; /* for channel list */
struct dentry *parent; /* parent dentry passed to open */
@ -204,7 +205,7 @@ static inline void relay_write(struct rchan *chan,
struct rchan_buf *buf;
local_irq_save(flags);
buf = chan->buf[smp_processor_id()];
buf = *this_cpu_ptr(chan->buf);
if (unlikely(buf->offset + length > chan->subbuf_size))
length = relay_switch_subbuf(buf, length);
memcpy(buf->data + buf->offset, data, length);
@ -230,12 +231,12 @@ static inline void __relay_write(struct rchan *chan,
{
struct rchan_buf *buf;
buf = chan->buf[get_cpu()];
buf = *get_cpu_ptr(chan->buf);
if (unlikely(buf->offset + length > buf->chan->subbuf_size))
length = relay_switch_subbuf(buf, length);
memcpy(buf->data + buf->offset, data, length);
buf->offset += length;
put_cpu();
put_cpu_ptr(chan->buf);
}
/**
@ -251,17 +252,19 @@ static inline void __relay_write(struct rchan *chan,
*/
static inline void *relay_reserve(struct rchan *chan, size_t length)
{
void *reserved;
struct rchan_buf *buf = chan->buf[smp_processor_id()];
void *reserved = NULL;
struct rchan_buf *buf = *get_cpu_ptr(chan->buf);
if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
length = relay_switch_subbuf(buf, length);
if (!length)
return NULL;
goto end;
}
reserved = buf->data + buf->offset;
buf->offset += length;
end:
put_cpu_ptr(chan->buf);
return reserved;
}