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Thomas Richter 6c481031c9 perf test: Fix 'Simple expression parser' test on arch without CPU die topology info 
Some platforms do not have CPU die support, for example s390.

Commit
Cc: Ian Rogers <irogers@google.com>
Fixes: fdf1e29b61 ("perf expr: Add metric literals for topology.")
fails on s390:

  # perf test -Fv 7
    ...
  # FAILED tests/expr.c:173 #num_dies >= #num_packages
    ---- end ----
    Simple expression parser: FAILED!
  #

Investigating this issue leads to these functions:

 build_cpu_topology()
   +--> has_die_topology(void)
        {
           struct utsname uts;

           if (uname(&uts) < 0)
                  return false;
           if (strncmp(uts.machine, "x86_64", 6))
                  return false;
           ....
        }

which always returns false on s390. The caller build_cpu_topology()
checks has_die_topology() return value. On false the the struct
cpu_topology::die_cpu_list is not contructed and has zero entries. This
leads to the failing comparison: #num_dies >= #num_packages.  s390 of
course has a positive number of packages.

Fix this and check if the function build_cpu_topology() did build up
a die_cpus_list. The number of entries in this list should be larger
than 0. If the number of list element is zero, the die_cpus_list has
not been created and the check in function test__expr():

    TEST_ASSERT_VAL("#num_dies >= #num_packages", \
		    num_dies >= num_packages)

always fails.

Output after:

  # perf test -Fv 7
   7: Simple expression parser                                        :
   --- start ---
   division by zero
   syntax error
   ---- end ----
   Simple expression parser: Ok
  #

Fixes: fdf1e29b61 ("perf expr: Add metric literals for topology.")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20211129112339.3003036-1-tmricht@linux.ibm.com
[ Added comment in the added 'if (num_dies)' line about architectures not having die topology ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2021-12-06 21:57:53 -03:00
arch EFI fix for v5.16 2021-12-06 10:09:00 -08:00
block block: call rq_qos_done() before ref check in batch completions 2021-11-26 09:53:23 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation A few important documentation fixes, including breakage that comes with 2021-12-06 10:46:20 -08:00
drivers parisc architecture bug and warning fixes for kernel v5.16-rc4 2021-12-05 12:58:18 -08:00
fs Fixes for 5.16-rc3: 2021-12-04 17:22:53 -08:00
include regulator: Documentation fix for v5.16 2021-12-06 10:14:12 -08:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel - Prevent a tick storm when a dedicated timekeeper CPU in nohz_full 2021-12-05 08:58:52 -08:00
lib siphash: use _unaligned version by default 2021-11-29 19:50:50 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Fixes for 5.16 folios: 2021-11-25 10:13:56 -08:00
net Networking fixes for 5.16-rc4, including fixes from wireless, 2021-12-02 11:22:06 -08:00
samples s390 updates for 5.16-rc2 2021-11-20 10:55:50 -08:00
scripts Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2021-11-24 09:44:13 -08:00
security selinux: fix NULL-pointer dereference when hashtab allocation fails 2021-11-19 16:11:39 -05:00
sound sound fixes for 5.16-rc4 2021-12-01 10:07:39 -08:00
tools perf test: Fix 'Simple expression parser' test on arch without CPU die topology info 2021-12-06 21:57:53 -03:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-11-26 06:43:28 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: update email address of Christian Borntraeger 2021-11-18 17:50:54 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS TTY/Serial fixes for 5.16-rc4 2021-12-05 09:13:20 -08:00
Makefile Makefile: Do not quote value for CONFIG_CC_IMPLICIT_FALLTHROUGH 2021-12-06 16:42:47 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.