Re: [PATCH v5 06/12] seq_buf: Add seq_buf_strlen()

[Steven Rostedt]

On Thu, 22 Oct 2026 23:02:36 +0200
Alejandro Colomar <alx+linux-hardening@xxxxxxxxxx> wrote:

> > 
> > I rather not increase its size. It is embedded in the trace_seq.  
> 
> The size shouldn't change:
> 
> 	alx@debian:~/tmp$ cat seq_buf_size_comparison.c 
> 	#include <stddef.h>
> 	#include <stdio.h>
> 
> 	struct seq_buf {
> 		char    *buffer;
> 		size_t  size;
> 		size_t  len;
> 	};
> 
> 	struct alx_seq_buf {
> 		char  *buffer;
> 		char  *p;
> 		char  *end;
> 	};

OK, I was thinking you were adding another pointer.

> 
> 	int
> 	main(void)
> 	{
> 		printf("%zu\n", sizeof(struct seq_buf));
> 		printf("%zu\n", sizeof(struct alx_seq_buf));
> 	}
> 	alx@debian:~/tmp$ gcc -Wall -Wextra seq_buf_size_comparison.c 
> 	alx@debian:~/tmp$ ./a.out 
> 	24
> 	24
> 
> size_t and pointers should always have the same size, so this doesn't
> change the size.
> 
> Am I missing something?
> 
> 
> Cheers,
> Alex
> 
> > Yes the seq_buf code can be complex, but it's in one location where it can
> > be highly tested and verified. The point of seq_buf is to do the complexity
> > so that other places in the kernel doesn't need to.

We could look into updating it to pointers later, but right now I
rather keep what we have. Let's focus first on the new stuff. It's not
that hard to validate.

-- Steve