Hello Julia,
On Wednesday, May 2, 2018, 4:37:29 PM CEST Julia Cartwright wrote:
> [..]
> > +++ b/fs/squashfs/Kconfig
> > @@ -86,6 +86,7 @@ config SQUASHFS_DECOMP_MULTI
> >
> > config SQUASHFS_DECOMP_MULTI_PERCPU
> > bool "Use percpu multiple decompressors for parallel I/O"
> > + depends on !PREEMPT_RT_BASE
>
> Hmm, I think we'd like to get out of the business of disabling Kconfig
> options unless we are absolutely not given any other choice.
>
> Looking at the codepaths involved in this squashfs decompressor, it
> seems like this is a perfect candidate for the usage of local locks.
> Can you give the following patch a try instead?
Sure. See below!
> --- a/fs/squashfs/decompressor_multi_percpu.c
> +++ b/fs/squashfs/decompressor_multi_percpu.c
> @@ -6,6 +6,7 @@
> * the COPYING file in the top-level directory.
> */
>
> +#include <linux/locallock.h>
> #include <linux/types.h>
> #include <linux/slab.h>
> #include <linux/percpu.h>
<linux/locallock.h> needs to be added after <linux/slab.h>.
> [...]
> @@ -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_var(stream_lock, percpu);
> +
> + res = msblk->decompressor->decompress(msblk, stream->stream, bh, b,
> + offset, length, output);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This doesn't work. I get a "Unable to handle kernel paging request at virtual address bcf67c1c". addr2line says its this line.
Best regards,
Alexander
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
