Add comment describing ioctl number duplication

[lttng-tools.git] / src / common / kernel-ctl / kernel-ioctl.h

diff --git a/src/common/kernel-ctl/kernel-ioctl.h b/src/common/kernel-ctl/kernel-ioctl.h
index 15308ac40fe999ec9c9c5fc9b66972e89ec1af0d..68056dcf1279521e9fa6ed0a73fb8b2fc246a450 100644 (file)
--- a/src/common/kernel-ctl/kernel-ioctl.h
+++ b/src/common/kernel-ctl/kernel-ioctl.h
@@ -127,6 +127,11 @@
        _IOR(0xF6, 0x58, int32_t)
 #define LTTNG_KERNEL_SESSION_UNTRACK_PID       \
        _IOR(0xF6, 0x59, int32_t)
+/*
+ * ioctl 0x58 and 0x59 are duplicated here. It works, since _IOR vs _IO
+ * are generating two different ioctl numbers, but this was not done on
+ * purpose. We should generally try to avoid those duplications.
+ */
 #define LTTNG_KERNEL_SESSION_LIST_TRACKER_PIDS _IO(0xF6, 0x58)
 #define LTTNG_KERNEL_SESSION_METADATA_REGEN    _IO(0xF6, 0x59)