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| author | Julia Cartwright <julia@ni.com> | 2018-05-07 08:58:57 -0500 |
|---|---|---|
| committer | Luis Claudio R. Goncalves <lgoncalv@redhat.com> | 2021-10-11 07:51:28 -0300 |
| commit | 4689b18c484fd3be63f458be507e74f66d7bc1a8 (patch) | |
| tree | feebe8c666191f109ca438db50dfb4349f69ee7f | |
| parent | 0f0b496de69b7ad9c31a6cf1a604b8dd893802cf (diff) | |
| download | linux-rt-4689b18c484fd3be63f458be507e74f66d7bc1a8.tar.gz | |
squashfs: make use of local lock in multi_cpu decompressor
Currently, the squashfs multi_cpu decompressor makes use of
get_cpu_ptr()/put_cpu_ptr(), which unconditionally disable preemption
during decompression.
Because the workload is distributed across CPUs, all CPUs can observe a
very high wakeup latency, which has been seen to be as much as 8000us.
Convert this decompressor to make use of a local lock, which will allow
execution of the decompressor with preemption-enabled, but also ensure
concurrent accesses to the percpu compressor data on the local CPU will
be serialized.
Cc: stable-rt@vger.kernel.org
Reported-by: Alexander Stein <alexander.stein@systec-electronic.com>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
(cherry picked from commit c160736542d7b3d67da32848d2f028b8e35730e5)
Signed-off-by: Julia Cartwright <julia@ni.com>
| -rw-r--r-- | fs/squashfs/decompressor_multi_percpu.c | 16 |
1 files changed, 12 insertions, 4 deletions
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", |