Hello Julia,
On Thursday, May 3, 2018, 5:48:34 PM CEST Julia Cartwright wrote:
> [...]
> Hrmph. I was lost in the percpu arithmetic. Should have built with
> sparse, it clearly tells me I screwed up. Are you able to give this a
> try? It's sparse-clean now :)
That does the trick. The max latency stays at 80µs in my test case. Thanks.
Tested-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx>
Best regards,
Alexander
> diff --git a/fs/squashfs/decompressor_multi_percpu.c b/fs/squashfs/decompressor_multi_percpu.c
> index 23a9c28ad8ea..6a73c4fa88e7 100644
> --- a/fs/squashfs/decompressor_multi_percpu.c
> +++ b/fs/squashfs/decompressor_multi_percpu.c
> @@ -10,6 +10,7 @@
> #include <linux/slab.h>
> #include <linux/percpu.h>
> #include <linux/buffer_head.h>
> +#include <linux/locallock.h>
>
> #include "squashfs_fs.h"
> #include "squashfs_fs_sb.h"
> @@ -25,6 +26,8 @@ struct squashfs_stream {
> void *stream;
> };
>
> +static DEFINE_LOCAL_IRQ_LOCK(stream_lock);
> +
> void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
> void *comp_opts)
> {
> @@ -79,10 +82,15 @@ int squashfs_decompress(struct squashfs_sb_info *msblk, struct buffer_head **bh,
> {
> struct squashfs_stream __percpu *percpu =
> (struct squashfs_stream __percpu *) msblk->stream;
> - struct squashfs_stream *stream = get_cpu_ptr(percpu);
> - int res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
> - offset, length, output);
> - put_cpu_ptr(stream);
> + struct squashfs_stream *stream;
> + int res;
> +
> + stream = get_locked_ptr(stream_lock, percpu);
> +
> + res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
> + offset, length, output);
> +
> + put_locked_ptr(stream_lock, stream);
>
> if (res < 0)
> ERROR("%s decompression failed, data probably corrupt\n",
> diff --git a/include/linux/locallock.h b/include/linux/locallock.h
> index d658c2552601..c3ab5183a6a1 100644
> --- a/include/linux/locallock.h
> +++ b/include/linux/locallock.h
> @@ -222,6 +222,14 @@ static inline int __local_unlock_irqrestore(struct local_irq_lock *lv,
>
> #define put_locked_var(lvar, var) local_unlock(lvar);
>
> +#define get_locked_ptr(lvar, var) \
> + ({ \
> + local_lock(lvar); \
> + this_cpu_ptr(var); \
> + })
> +
> +#define put_locked_ptr(lvar, var) local_unlock(lvar);
> +
> #define local_lock_cpu(lvar) \
> ({ \
> local_lock(lvar); \
>
>
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