Thank you for the review, Kazu.

On Wed, Jan 26, 2022 at 1:07 PM HAGIO KAZUHITO(萩尾 一仁) <[email protected]>
wrote:

> -----Original Message-----
> > On Tue, Jan 25, 2022 at 10:28 AM HAGIO KAZUHITO(萩尾 一仁) <
> [email protected] <mailto:[email protected]>
> > > 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 <[email protected] <mailto:
> [email protected]> >
> >       > ---
> >       >  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
> >
>
>
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