[lustre-devel] [PATCH v3 04/13] lustre: libcfs: fix cfs_print_to_console()

[NeilBrown]

On Fri, Jun 29 2018, James Simmons wrote:

>> > The original code for cfs_print_to_console() used printk() and
>> > used tricks to select which printk level to use. Later a cleanup
>> > patch landed the just converted printk directly to pr_info which
>> > is not exactly correct. Instead of converting back to printk lets
>> > move everything to pr_* type functions which simplify the code.
>> > This allows us to fold both dbghdr_to_err_string() and the
>> > function dbghdr_to_info_string() into cfs_print_to_console().
>> > 
>> > Signed-off-by: James Simmons <jsimmons at infradead.org>
>> > ---
>> > .../staging/lustre/lnet/libcfs/linux-tracefile.c   | 55 ++++++----------------
>> > 1 file changed, 14 insertions(+), 41 deletions(-)
>> > 
>> > diff --git a/drivers/staging/lustre/lnet/libcfs/linux-tracefile.c b/drivers/staging/lustre/lnet/libcfs/linux-tracefile.c
>> > index 3af7722..c1747c4 100644
>> > --- a/drivers/staging/lustre/lnet/libcfs/linux-tracefile.c
>> > +++ b/drivers/staging/lustre/lnet/libcfs/linux-tracefile.c
>> > @@ -140,54 +140,27 @@ enum cfs_trace_buf_type cfs_trace_buf_idx_get(void)
>> > void cfs_print_to_console(struct ptldebug_header *hdr, int mask,
>> > 			  const char *buf, int len, const char *file,
>> > 			  const char *fn)
>> > {
>> > +	char *prefix = "Lustre";
>> > +
>> > +	if (hdr->ph_subsys == S_LND || hdr->ph_subsys == S_LNET)
>> > +		prefix = "LNet";
>> > 
>> > -	if (mask & D_EMERG) {
>> > -		prefix = dbghdr_to_err_string(hdr);
>> > -		ptype = KERN_EMERG;
>> > +	if (mask & (D_CONSOLE | libcfs_printk)) {
>> 
>> This check is broken.  The default value of libcfs_printk (the mask
>> that controls which messages should be printed to the console, and
>> which ones should only be logged into the internal buffer) is:
>> 
>>     #define D_CANTMASK (D_ERROR | D_EMERG | D_WARNING | D_CONSOLE)
>> 
>> so that means virtually every console message will be printed with
>> pr_info() because this is matched first, instead of pr_emerg() or
>> pr_err() below.
>> 
>> That is why the previous code was matching D_EMERG and D_ERROR first,
>> then D_WARNING, and (D_CONSOLE | libcfs_printk) at the end.
>
> So to do this right we need:
>
> static void cfs_print_to_console(struct ptldebug_header *hdr, int mask,
>                                  const char *buf, int len, const char 
> *file,
>                                  const char *fn)
> {
>         char *prefix = "Lustre";
>
>         if (hdr->ph_subsys == S_LND || hdr->ph_subsys == S_LNET)
>                 prefix = "LNet";
>
>         if (mask & D_CONSOLE) {
>                 if (mask & D_EMERG) {
>                         pr_emerg("%sError: %.*s", prefix, len, buf);
>                 } else if (mask & D_ERROR) {
>                         pr_err("%sError: %.*s", prefix, len, buf);
>                 } else if (mask & D_WARNING) {
>                         pr_warn("%s: %.*s", prefix, len, buf);
>                 } else if (mask & libcfs_printk) {
>                         pr_info("%s: %.*s", prefix, len, buf);
>                 }
>         } else {
>                 if (mask & D_EMERG) {
>                         pr_emerg("%sError: %d:%d:(%s:%d:%s()) %.*s", prefix,
>                                  hdr->ph_pid, hdr->ph_extern_pid, file,
>                                  hdr->ph_line_num, fn, len, buf);
>                 } else if (mask & D_ERROR) {
>                         pr_err("%sError: %d:%d:(%s:%d:%s()) %.*s", prefix,
>                                hdr->ph_pid, hdr->ph_extern_pid, file,
>                                hdr->ph_line_num, fn, len, buf);
>                 } else if (mask & D_WARNING) {
>                         pr_warn("%s: %d:%d:(%s:%d:%s()) %.*s", prefix,
>                                 hdr->ph_pid, hdr->ph_extern_pid, file,
>                                 hdr->ph_line_num, fn, len, buf);
>                 } else if (mask & libcfs_printk) {
>                         pr_info("%s: %.*s", prefix, len, buf);
>                 }
>         }
> }

That doesn't look right either.
The original code would *always* print something.
This code looks like it might not (e.g. for mask == 0).

What is "D_CONSOLE" suppose to mean?  It seems to me "make the messages
less verbose" and it isn't clear to me that what is called "D_CONSOLE".

Thanks,
NeilBrown
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