Thank you for the review, Kazu.

On Wed, Jan 26, 2022 at 1:07 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@nec.com> wrote:
-----Original Message-----
> On Tue, Jan 25, 2022 at 10:28 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@nec.com <mailto:k-hagio-ab@nec.com>
> > wrote:
>
>
>       Hi Lianbo,
>
>       thanks for working on this.
>
>       -----Original Message-----
>       > Kernel commit <80ee81e0403c> ("bpf: Eliminate rlimit-based memory
>       > accounting infra for bpf maps") removed the struct bpf_map_memory
>       > member from struct bpf_map. Without the patch, "bpf -m|-M" options
>       > will print the following errors:
>       >
>       > crash> bpf -m 1
>       >  ID      BPF_MAP          BPF_MAP_TYPE     MAP_FLAGS
>       >  1   ffff96ba41804400        ARRAY          00000000
>       >      KEY_SIZE: 4  VALUE_SIZE: 8  MAX_ENTRIES: 64  MEMLOCK: (unknown)
>       >                                                           ^^^^^^^
>       >      NAME: "dist"  UID: (unknown)
>       >                          ^^^^^^^
>       >
>       > Signed-off-by: Lianbo Jiang <lijiang@redhat.com <mailto:lijiang@redhat.com> >
>       > ---
>       >  bpf.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>       >  1 file changed, 64 insertions(+), 3 deletions(-)
>       >
>       > diff --git a/bpf.c b/bpf.c
>       > index cb6b0ed385f9..d45e9ab9311b 100644
>       > --- a/bpf.c
>       > +++ b/bpf.c
>       > @@ -15,6 +15,7 @@
>       >   */
>       >
>       >  #include "defs.h"
>       > +#include <stdbool.h>
>       >
>       >  struct bpf_info {
>       >       ulong status;
>       > @@ -63,6 +64,66 @@ static int do_old_idr(int, ulong, struct list_pair *);
>       >  #define PROG_VERBOSE  (0x40)
>       >  #define MAP_VERBOSE   (0x80)
>       >
>       > +static bool map_is_per_cpu(ulong type)
>
>       I think that int is enough here and stdbool.h can be removed.
>
>       (also type is int originally.)
>
>
>
> Thank you for the comment and suggestions, Kazu.
>
> Other several changes look good to me, But there are two issues, I have the following comments.
>
>
>
>       > +{
>       > +     /*
>       > +      * See the definition of bpf_map_type:
>       > +      * include/uapi/linux/bpf.h
>       > +      */
>       > +     #define BPF_MAP_TYPE_PERCPU_HASH (5UL)
>       > +     #define BPF_MAP_TYPE_PERCPU_ARRAY (6UL)
>       > +     #define BPF_MAP_TYPE_LRU_PERCPU_HASH (10UL)
>       > +     #define BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE (21UL)
>
>       This #define style in function looks unusual.. please let me change.
>
>
>
> The above code style is intentional, the intention is to enhance the readability of this code, and the
> important thing is that these #define macros are not used in the other functions.
>
> In addition, it has the same #define style in crash utility functions, such as the netdump_memory_dump().
> And the similar definitions can also be found in other c source files, for example: set_kvm_iohole(),
> symbol_dump(), show_ps_summary()...
>
> int
> netdump_memory_dump(FILE *fp)
> {
> ...
> #define DUMP_EXCLUDE_CACHE 0x00000001   /* Exclude LRU & SwapCache pages*/
> #define DUMP_EXCLUDE_CLEAN 0x00000002   /* Exclude all-zero pages */
> #define DUMP_EXCLUDE_FREE  0x00000004   /* Exclude free pages */
> #define DUMP_EXCLUDE_ANON  0x00000008   /* Exclude Anon pages */
> #define DUMP_SAVE_PRIVATE  0x00000010   /* Save private pages */
>
>                         others = 0;
>
> ...
> }
>
> Furthermore, the same style can be seen in the upstream kernels. :-)

ok, that's fine with me.  If you do so, could you remove the indents
at the beginning of a line?  I've not seen this style in function.


Yes, sure, I will remove the indents.
 
> +     #define BPF_MAP_TYPE_PERCPU_HASH (5UL)
> +     #define BPF_MAP_TYPE_PERCPU_ARRAY (6UL)
> +     #define BPF_MAP_TYPE_LRU_PERCPU_HASH (10UL)
> +     #define BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE (21UL)
   ^^^^^

Thank you for pointing out this issue.
 


>
>
>
>       > +
>       > +     return type == BPF_MAP_TYPE_PERCPU_HASH ||
>       > +            type == BPF_MAP_TYPE_PERCPU_ARRAY ||
>       > +            type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
>       > +            type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE;
>       > +}
>       > +
>       > +static bool map_is_fd_map(ulong type)
>       > +{
>       > +     /*
>       > +      * See the definition of bpf_map_type:
>       > +      * include/uapi/linux/bpf.h
>       > +      */
>       > +     #define BPF_MAP_TYPE_PROG_ARRAY (3UL)
>       > +     #define BPF_MAP_TYPE_PERF_EVENT_ARRAY (4UL)
>       > +     #define BPF_MAP_TYPE_CGROUP_ARRAY (8UL)
>       > +     #define BPF_MAP_TYPE_ARRAY_OF_MAPS (12UL)
>       > +     #define BPF_MAP_TYPE_HASH_OF_MAPS (13UL)
>
>       Ditto.
>
>       > +
>       > +     return type == BPF_MAP_TYPE_PROG_ARRAY ||
>       > +            type == BPF_MAP_TYPE_PERF_EVENT_ARRAY ||
>       > +            type == BPF_MAP_TYPE_CGROUP_ARRAY ||
>       > +            type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
>       > +            type == BPF_MAP_TYPE_HASH_OF_MAPS;
>       > +
>       > +}
>       > +
>       > +static ulong bpf_map_memory_size(ulong map_type, ulong vsize, ulong ksize, ulong esize)
>
>       The arguments are int and uint, and let's sync with kernel for readability.
>
>       static ulong bpf_map_memory_size(int map_type, uint value_size,
>                                       uint key_size, uint max_entries)
>
>       > +{
>       > +     ulong memsize,valsize;
>       > +     int cpus = 0;
>       > +
>       > +     valsize = vsize;
>       > +
>       > +     if (map_is_fd_map(map_type))
>       > +             valsize = sizeof(ulong);
>
>       This should be uint.
>
>               else if (IS_FD_MAP(map))
>                       return sizeof(u32);
>
>       > +
>       > +     if (map_is_per_cpu(map_type)) {
>       > +             cpus = get_cpus_possible();
>       > +             if (!cpus)
>       > +                     error(WARNING, "cpu_possible_map does not exist, pissible cpus: %d\n",
> cpus);
>
>       s/pissible/possible/
>
>       And if this fails, I think it would be better to print "(unknown)", so
>       let's return 0 here.
>
>
>
> When the cpu_possible_map does not exist, could it be better to set the default number of cpus to 1?  In
> fact, it has at least one cpu even if the get_cpus_possible() failed. It may not be an exact value, but
> it is the closest value for the memlock(with a warning).
>
> And the value of memlock itself is approximate, not a completely exact value. What do you think?

The value is an approximation, but it's the same as bpftool command output
and this is an important aspect.  I think that it's better to print "(unknown)"
if they can be wrong, because they can be confusing/misleading to users.

Sounds good. 

Thanks.
Lianbo

 

Thanks,
Kazu


>
>
>
>       > +
>       > +             valsize = roundup(vsize, 8) * cpus;
>       > +     }
>       > +
>       > +     memsize = roundup((ksize + valsize), 8);
>       > +
>       > +     return roundup((esize * memsize), PAGESIZE());
>       > +}
>       > +
>       >  void
>       >  cmd_bpf(void)
>       >  {
>       > @@ -332,7 +393,7 @@ do_bpf(ulong flags, ulong prog_id, ulong map_id, int radix)
>       >  {
>       >       struct bpf_info *bpf;
>       >       int i, c, found, entries, type;
>       > -     uint uid, map_pages, key_size, value_size, max_entries;
>       > +     uint uid, map_pages, key_size = 0, value_size = 0, max_entries = 0;
>       >       ulong bpf_prog_aux, bpf_func, end_func, addr, insnsi, user;
>       >       ulong do_progs, do_maps;
>       >       ulonglong load_time;
>       > @@ -603,7 +664,7 @@ do_map_only:
>       >                               map_pages = UINT(bpf->bpf_map_buf + OFFSET(bpf_map_pages));
>       >                               fprintf(fp, "%d\n", map_pages * PAGESIZE());
>       >                       } else
>       > -                             fprintf(fp, "(unknown)\n");
>       > +                             fprintf(fp, "%ld\n", bpf_map_memory_size(type, value_size,
> key_size,
>       > max_entries));
>
>       Then, how about this?
>
>       +                       } else if (memory = bpf_map_memory_size(type, value_size, key_size,
> max_entries))
>       +                               fprintf(fp, "%ld\n", memory);
>       +                       else
>       +                               fprintf(fp, "(unknown)");
>
>       I've attached a modified patch, could you check?
>
>
>
>
> Thank you for writing the patch in the attachment.
>
> Thanks.
> Lianbo
>
>
>
>
>       Thanks,
>       Kazu
>
>       >
>       >                       fprintf(fp, "     NAME: ");
>       >                       if (VALID_MEMBER(bpf_map_name)) {
>       > @@ -632,7 +693,7 @@ do_map_only:
>       >                               else
>       >                                       fprintf(fp, "(unknown)\n");
>       >                       } else
>       > -                             fprintf(fp, "(unknown)\n");
>       > +                             fprintf(fp, "(unused)\n");
>       >               }
>       >
>       >               if (flags & DUMP_STRUCT) {
>       > --
>       > 2.20.1
>