linux-kernel - Re: [PATCH 2/3] fs/pstore: fs/squashfs: Change lz4 compressor functions to work with new version

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Date:   Thu, 22 Dec 2016 22:21:09 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Sven Schmidt <4sschmid@...ormatik.uni-hamburg.de>
Cc:     akpm@...ux-foundation.org, bongkyu.kim@....com,
        sergey.senozhatsky@...il.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] fs/pstore: fs/squashfs: Change lz4 compressor
 functions to work with new version

On (12/20/16 19:53), Sven Schmidt wrote:
> @@ -366,7 +366,7 @@ static int decompress_lz4(void *in, void *out, size_t inlen, size_t outlen)
>  
>  static void allocate_lz4(void)
>  {
> -	big_oops_buf_sz = lz4_compressbound(psinfo->bufsize);
> +	big_oops_buf_sz = LZ4_compressBound(psinfo->bufsize);
>  	big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
>  	if (big_oops_buf) {
>  		workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
> @@ -493,7 +493,6 @@ static void pstore_dump(struct kmsg_dumper *dumper,
>  		if (!is_locked) {
>  			pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
>  				       , in_nmi() ? "NMI" : why);
> -			return;

why did you remove this "failed to lock buf in critical path" return?


>  		}
>  	} else {
>  		spin_lock_irqsave(&psinfo->buf_lock, flags);
> @@ -585,8 +584,8 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
>  		} else {
>  			spin_lock_irqsave(&psinfo->buf_lock, flags);
>  		}
> -		psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
> -				  s, 0, c, psinfo);
> +		memcpy(psinfo->buf, s, c);
> +		psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);

why extra memcpy()?

	-ss

>  		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
>  		s += c;
>  		c = e - s;
> diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
> index ff4468b..c087a63 100644
> --- a/fs/squashfs/lz4_wrapper.c
> +++ b/fs/squashfs/lz4_wrapper.c
> @@ -108,8 +108,7 @@ static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
>  		put_bh(bh[i]);
>  	}
>  
> -	res = lz4_decompress_unknownoutputsize(stream->input, length,
> -					stream->output, &dest_len);
> +	res = LZ4_decompress_safe(stream->input, stream->output, length, (int)dest_len);
>  	if (res)
>  		return -EIO;