On Fri, 2014-11-07 at 12:01 +0000, Daniel Thompson wrote: > Currently when kdb traps printk messages then the raw log level prefix > (consisting of '\001' followed by a numeral) does not get stripped off > before the message is issued to the various I/O handlers supported by > kdb. This causes annoying visual noise as well as causing problems > grepping for ^. It is also a change of behaviour compared to normal usage > of printk() usage. For example <SysRq>-h ends up with different output to > that of kdb's "sr h". > > This patch addresses the problem by stripping log levels from messages > before they are issued to the I/O handlers. printk() which can also > act as an i/o handler in some cases is special cased; if the caller > provided a log level then this will be preserved when sent to printk(). > > The addition of non-printable characters to the output of kdb commands is a > regression, albeit and extremely elderly one, introduced by commit > 04d2c8c83d0e ("printk: convert the format for KERN_<LEVEL> to a 2 byte > pattern"). Note also that this patch does *not* restore the original > behaviour from v3.5. Instead it makes printk() from within a kdb command > display the message without any prefix (i.e. like printk() normally does). [] > diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c [] > @@ -711,7 +712,10 @@ kdb_printit: > if (logging) { > saved_loglevel = console_loglevel; > console_loglevel = CONSOLE_LOGLEVEL_SILENT; > - printk(KERN_INFO "%s", kdb_buffer); > + if (cp == kdb_buffer) > + printk(KERN_INFO "%s", kdb_buffer); > + else > + printk("%s", kdb_buffer); The first part of the patch seem fine, but I'm confused about this bit above. Here, isn't the "if (cp == kdb_buffer)" unnecessary? if "(cp != kdb_buffer)", the buffer does have a prefix and it's emitted. If (cp == kdb_buffer), the buffer does _not_ have a prefix (meaning it's either a naked printk or a continuation line. (KERN_CONT is "") So why insert KERN_INFO? I believe the code should be: - printk(KERN_INFO "%s", kdb_buffer); + printk("%s", kdb_buffer); -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html