diff options
Diffstat (limited to 'debian/patches-rt/0173-squashfs-make-use-of-local-lock-in-multi_cpu-decompr.patch')
| -rw-r--r-- | debian/patches-rt/0173-squashfs-make-use-of-local-lock-in-multi_cpu-decompr.patch | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/debian/patches-rt/0173-squashfs-make-use-of-local-lock-in-multi_cpu-decompr.patch b/debian/patches-rt/0173-squashfs-make-use-of-local-lock-in-multi_cpu-decompr.patch new file mode 100644 index 000000000..e885134f9 --- /dev/null +++ b/debian/patches-rt/0173-squashfs-make-use-of-local-lock-in-multi_cpu-decompr.patch @@ -0,0 +1,72 @@ +From 98873b747e4321516bb428c214fde307593e19f8 Mon Sep 17 00:00:00 2001 +From: Julia Cartwright <julia@ni.com> +Date: Mon, 7 May 2018 08:58:57 -0500 +Subject: [PATCH 173/347] squashfs: make use of local lock in multi_cpu + decompressor +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +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> +--- + fs/squashfs/decompressor_multi_percpu.c | 16 ++++++++++++---- + 1 file 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", +-- +2.36.1 + |