Re: [PATCH v2] tracing: Make is_signed_type() compatible with sparse

[David Laight <david.laight.linux@gmail.com>]

On Wed, 2 Sep 2026 09:44:49 -0700
Bart Van Assche <bvanassche@acm.org> wrote:

> On 9/2/26 9:39 AM, Steven Rostedt wrote:
> > On Wed, 2 Sep 2026 09:31:41 -0700
> > Bart Van Assche <bvanassche@acm.org> wrote:
> >   
> >> $  git grep -nHE '__field.*(blk_opf_t|enum req_op)' include/trace
> >> include/trace/events/f2fs.h:1185:		__field(enum req_op, op)
> >> include/trace/events/f2fs.h:1186:		__field(blk_opf_t, op_flags)
> >> include/trace/events/f2fs.h:1241:		__field(enum req_op,	op)
> >> include/trace/events/f2fs.h:1242:		__field(blk_opf_t,	op_flags)
> >> include/trace/events/jbd2.h:364:		__field(    blk_opf_t,  write_flags		)
> >> include/trace/events/nilfs2.h:207:		    __field_struct(enum req_op, mode)  
> > 
> > Perhaps these should be converted to normal types and assigned with
> > __force. There's no reason to have the value in the ring buffer be of a
> > __bitwise type.  

There are already a shed load (or two) of __force casts in the defines
(further up the same file) that handle some of those fields.
They probably go away if the __field() used u32 and any casts added to
the TP_fast_assign() expansion instead.

> Yikes. Typecasts in general and __force casts in particular should be 
> avoided whenever possible, isn't it?

Anything __bitwise is pretty much going to need an __force cast before the
value can be actually used.
But the syntax should have been __force(type, value) so that the compiler
doesn't see a cast.

David
 
> 
> Bart.