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Levin" To: Steven Rostedt Cc: Vincent Donnefort , David Hildenbrand , linux-api@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] uapi: change TRACE_MMAP_IOCTL_GET_READER to avoid collision with TCGETS Message-ID: <20240630213626.GA23566@altlinux.org> MIME-Version: 1.0 Content-Disposition: inline X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5FABC180005 X-Stat-Signature: rsyz11uqbbna678zyzht6iq3koueym1n X-Rspam-User: X-HE-Tag: 1719783388-980038 X-HE-Meta: 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 9mb5xZ4T vloRyts2J9I1dDYpDZYuvTcKrWhTXJNWBaZm0Ilx3/IOjmOf03A/u7wf3KiPkrXrnxeID/iXA+7A/GlX6R/e/h+1i9rkadF0x2uPOBFzvLvXNErQ7fWqW8i/kJR6D6JzA8xgCCWG6B12g29w8MvREdLNIJryLV11b9liG1bYGaAuoCqYSF+26RowN55lil8EieetCH5k7uLwEGGwIBRY+KzgL1TrnfZTaWxFJjurO5PjoK95SjtdMa2Z9I0jgAa5vVquIL+uXzh29m779s00t/pEOmeGJb0zOgw6I/7xoglToAPvQSnuKY5RWbyZzbo12y6Nk X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 --- include/uapi/linux/trace_mmap.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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_ */