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tracing: Fix ioctl conflict with memmapped ring buffer ioctl

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It was reported that the ioctl() number used to update the ring buffer
 memory mapping conflicted with the TCGETS ioctl causing strace to report:
 
   $ strace -e ioctl stty
   ioctl(0, TCGETS or TRACE_MMAP_IOCTL_GET_READER, {c_iflag=ICRNL|IXON, c_oflag=NL0|CR0|TAB0|BS0|VT0|FF0|OPOST|ONLCR, c_cflag=B38400|CS8|CREAD, c_lflag=ISIG|ICANON|ECHO|ECHOE|ECHOK|IEXTEN|ECHOCTL|ECHOKE, ...}) = 0
 
 Since this ioctl hasn't been in a full release yet, change it from "T", 0x1
 to "R" 0x20, and also reserve 0x20-0x2F for future ioctl commands, as
 some more are being worked on for the future.
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Merge tag 'trace-v6.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fix from Steven Rostedt:
 "Fix ioctl conflict with memmapped ring buffer ioctl

  It was reported that the ioctl() number used to update the ring buffer
  memory mapping conflicted with the TCGETS ioctl causing strace to
  report:

    $ strace -e ioctl stty
    ioctl(0, TCGETS or TRACE_MMAP_IOCTL_GET_READER, {c_iflag=ICRNL|IXON, c_oflag=NL0|CR0|TAB0|BS0|VT0|FF0|OPOST|ONLCR, c_cflag=B38400|CS8|CREAD, c_lflag=ISIG|ICANON|ECHO|ECHOE|ECHOK|IEXTEN|ECHOCTL|ECHOKE, ...}) = 0

  Since this ioctl hasn't been in a full release yet, change it from
  "T", 0x1 to "R" 0x20, and also reserve 0x20-0x2F for future ioctl
  commands, as some more are being worked on for the future"

* tag 'trace-v6.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Have memmapped ring buffer use ioctl of "R" range 0x20-2F
This commit is contained in:
Linus Torvalds 2024-07-03 14:54:35 -07:00
commit 795c58e4c7
2 changed files with 2 additions and 1 deletions
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1
Documentation/userspace-api/ioctl/ioctl-number.rst
View File

@ -186,6 +186,7 @@ Code Seq# Include File Comments
'Q' all linux/soundcard.h
'R' 00-1F linux/random.h conflict!
'R' 01 linux/rfkill.h conflict!
'R' 20-2F linux/trace_mmap.h
'R' C0-DF net/bluetooth/rfcomm.h
'R' E0 uapi/linux/fsl_mc.h
'S' all linux/cdrom.h conflict!

2
include/uapi/linux/trace_mmap.h
View File

@ -43,6 +43,6 @@ struct trace_buffer_meta {
__u64 Reserved2;
};
#define TRACE_MMAP_IOCTL_GET_READER _IO('T', 0x1)
#define TRACE_MMAP_IOCTL_GET_READER _IO('R', 0x20)
#endif /* _TRACE_MMAP_H_ */