| Message ID | 20240630213626.GA23566@altlinux.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | uapi: change TRACE_MMAP_IOCTL_GET_READER to avoid collision with TCGETS | expand |
diff --git a/include/uapi/linux/trace_mmap.h b/include/uapi/linux/trace_mmap.h index bd1066754220..cb858f1b8367 100644 --- a/include/uapi/linux/trace_mmap.h +++ b/include/uapi/linux/trace_mmap.h @@ -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 _IOC(_IOC_NONE, 'T', 0x1, 0x1) #endif /* _TRACE_MMAP_H_ */
The number that was initially chosen for TRACE_MMAP_IOCTL_GET_READER, unfortunately, collides with TCGETS on most of architectures. For example, this is how strace output would look like when support for this value of TRACE_MMAP_IOCTL_GET_READER is added: $ 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 Even though ioctl numbers are inherently not unique, TCGETS is a very traditional one, so let's change the value of TRACE_MMAP_IOCTL_GET_READER a bit to avoid this collision. Given that _IO('T', 0x1) is _IOC(_IOC_NONE, 'T', 0x1, 0), something like _IOC(_IOC_NONE, 'T', 0x1, 0x1) should be OK. Fixes: cf9f0f7c4c5bb ("tracing: Allow user-space mapping of the ring-buffer") Signed-off-by: Dmitry V. Levin <ldv@strace.io> --- include/uapi/linux/trace_mmap.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)