s390/ptrace: clarify bits in the per_struct

The bits single_step and instruction_fetch lost their meaning
with git commit 5e9a26928f550157 "[S390] ptrace cleanup".
Clarify the comment for these two bits.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/s390/include/uapi/asm/ptrace.h b/arch/s390/include/uapi/asm/ptrace.h
index a150f4fabe43..77630c74f13b 100644
--- a/arch/s390/include/uapi/asm/ptrace.h
+++ b/arch/s390/include/uapi/asm/ptrace.h
@@ -359,9 +359,9 @@ typedef struct
                 per_cr_bits    bits;
         } control_regs;
         /*
-         * Use these flags instead of setting em_instruction_fetch
-         * directly they are used so that single stepping can be
-         * switched on & off while not affecting other tracing
+         * The single_step and instruction_fetch bits are obsolete,
+         * the kernel always sets them to zero. To enable single
+         * stepping use ptrace(PTRACE_SINGLESTEP) instead.
          */
         unsigned  single_step       : 1;
         unsigned  instruction_fetch : 1;