From: Stephen Boyd <swboyd@xxxxxxxxxxxx> Subject: lib/hexdump: make print_hex_dump_bytes() a nop on !DEBUG builds I'm seeing a bunch of debug prints from a user of print_hex_dump_bytes() in my kernel logs, but I don't have CONFIG_DYNAMIC_DEBUG enabled nor do I have DEBUG defined in my build. The problem is that print_hex_dump_bytes() calls a wrapper function in lib/hexdump.c that calls print_hex_dump() with KERN_DEBUG level. There are three cases to consider here 1. CONFIG_DYNAMIC_DEBUG=y --> call dynamic_hex_dum() 2. CONFIG_DYNAMIC_DEBUG=n && DEBUG --> call print_hex_dump() 3. CONFIG_DYNAMIC_DEBUG=n && !DEBUG --> stub it out Right now, that last case isn't detected and we still call print_hex_dump() from the stub wrapper. Let's make print_hex_dump_bytes() only call print_hex_dump_debug() so that it works properly in all cases. Case #1, print_hex_dump_debug() calls dynamic_hex_dump() and we get same behavior. Case #2, print_hex_dump_debug() calls print_hex_dump() with KERN_DEBUG and we get the same behavior. Case #3, print_hex_dump_debug() is a nop, changing behavior to what we want, i.e. print nothing. Link: http://lkml.kernel.org/r/20190816235624.115280-1-swboyd@xxxxxxxxxxxx Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/printk.h | 22 +++++++++++++++------- lib/hexdump.c | 21 --------------------- 2 files changed, 15 insertions(+), 28 deletions(-) --- a/include/linux/printk.h~lib-hexdump-make-print_hex_dump_bytes-a-nop-on-debug-builds +++ a/include/linux/printk.h @@ -488,13 +488,6 @@ extern int hex_dump_to_buffer(const void extern void print_hex_dump(const char *level, const char *prefix_str, int prefix_type, int rowsize, int groupsize, const void *buf, size_t len, bool ascii); -#if defined(CONFIG_DYNAMIC_DEBUG) -#define print_hex_dump_bytes(prefix_str, prefix_type, buf, len) \ - dynamic_hex_dump(prefix_str, prefix_type, 16, 1, buf, len, true) -#else -extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type, - const void *buf, size_t len); -#endif /* defined(CONFIG_DYNAMIC_DEBUG) */ #else static inline void print_hex_dump(const char *level, const char *prefix_str, int prefix_type, int rowsize, int groupsize, @@ -526,4 +519,19 @@ static inline void print_hex_dump_debug( } #endif +/** + * print_hex_dump_bytes - shorthand form of print_hex_dump() with default params + * @prefix_str: string to prefix each line with; + * caller supplies trailing spaces for alignment if desired + * @prefix_type: controls whether prefix of an offset, address, or none + * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE) + * @buf: data blob to dump + * @len: number of bytes in the @buf + * + * Calls print_hex_dump(), with log level of KERN_DEBUG, + * rowsize of 16, groupsize of 1, and ASCII output included. + */ +#define print_hex_dump_bytes(prefix_str, prefix_type, buf, len) \ + print_hex_dump_debug(prefix_str, prefix_type, 16, 1, buf, len, true) + #endif --- a/lib/hexdump.c~lib-hexdump-make-print_hex_dump_bytes-a-nop-on-debug-builds +++ a/lib/hexdump.c @@ -270,25 +270,4 @@ void print_hex_dump(const char *level, c } EXPORT_SYMBOL(print_hex_dump); -#if !defined(CONFIG_DYNAMIC_DEBUG) -/** - * print_hex_dump_bytes - shorthand form of print_hex_dump() with default params - * @prefix_str: string to prefix each line with; - * caller supplies trailing spaces for alignment if desired - * @prefix_type: controls whether prefix of an offset, address, or none - * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE) - * @buf: data blob to dump - * @len: number of bytes in the @buf - * - * Calls print_hex_dump(), with log level of KERN_DEBUG, - * rowsize of 16, groupsize of 1, and ASCII output included. - */ -void print_hex_dump_bytes(const char *prefix_str, int prefix_type, - const void *buf, size_t len) -{ - print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, 16, 1, - buf, len, true); -} -EXPORT_SYMBOL(print_hex_dump_bytes); -#endif /* !defined(CONFIG_DYNAMIC_DEBUG) */ #endif /* defined(CONFIG_PRINTK) */ _
