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[ Upstream commit03d309711d] Commit489338a717("perf tests evsel-tp-sched: Fix bitwise operator") causes test case 14 "Parse sched tracepoints fields" to fail on s390. This test succeeds on x86. In fact this test now fails on all architectures with type char treated as type unsigned char. The root cause is the signed-ness of character arrays in the tracepoints sched_switch for structure members prev_comm and next_comm. On s390 the output of: [root@m35lp76 perf]# cat /sys/kernel/debug/tracing/events/sched/sched_switch/format name: sched_switch ID: 287 format: field:unsigned short common_type; offset:0; size:2; signed:0; ... field:char prev_comm[16]; offset:8; size:16; signed:0; ... field:char next_comm[16]; offset:40; size:16; signed:0; reveals the character arrays prev_comm and next_comm are per default unsigned char and have values in the range of 0..255. On x86 both fields are signed as this output shows: [root@f29]# cat /sys/kernel/debug/tracing/events/sched/sched_switch/format name: sched_switch ID: 287 format: field:unsigned short common_type; offset:0; size:2; signed:0; ... field:char prev_comm[16]; offset:8; size:16; signed:1; ... field:char next_comm[16]; offset:40; size:16; signed:1; and the character arrays prev_comm and next_comm are per default signed char and have values in the range of -1..127. The implementation of type char is architecture specific. Since the character arrays in both tracepoints sched_switch and sched_wakeup should contain ascii characters, simply omit the check for signedness in the test case. Output before: [root@m35lp76 perf]# ./perf test -F 14 14: Parse sched tracepoints fields : --- start --- sched:sched_switch: "prev_comm" signedness(0) is wrong, should be 1 sched:sched_switch: "next_comm" signedness(0) is wrong, should be 1 sched:sched_wakeup: "comm" signedness(0) is wrong, should be 1 ---- end ---- 14: Parse sched tracepoints fields : FAILED! [root@m35lp76 perf]# Output after: [root@m35lp76 perf]# ./perf test -Fv 14 14: Parse sched tracepoints fields : --- start --- ---- end ---- Parse sched tracepoints fields: Ok [root@m35lp76 perf]# Fixes:489338a717("perf tests evsel-tp-sched: Fix bitwise operator") Signed-off-by: Thomas Richter <tmricht@linux.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Link: http://lkml.kernel.org/r/20190219153639.31267-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.