genirq/msi: Add abuse prevention comment to msi header

Hope dies last.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211206210749.170847844@linutronix.de

diff --git a/include/linux/msi.h b/include/linux/msi.h
index b54010ba7b0d9a16817abec52d4151d8a4838966..70cc6a555a8e6c0d2a2c519eacc00864340652a4 100644 (file)
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -2,6 +2,20 @@
 #ifndef LINUX_MSI_H
 #define LINUX_MSI_H
 
+/*
+ * This header file contains MSI data structures and functions which are
+ * only relevant for:
+ *     - Interrupt core code
+ *     - PCI/MSI core code
+ *     - MSI interrupt domain implementations
+ *     - IOMMU, low level VFIO, NTB and other justified exceptions
+ *       dealing with low level MSI details.
+ *
+ * Regular device drivers have no business with any of these functions and
+ * especially storing MSI descriptor pointers in random code is considered
+ * abuse. The only function which is relevant for drivers is msi_get_virq().
+ */
+
 #include <linux/cpumask.h>
 #include <linux/mutex.h>
 #include <linux/list.h>