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| author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-12-05 13:12:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-12-06 16:55:18 +0100 |
| commit | 64f6a5d1922bf6d2b2d845de20d4563a6f328e2d (patch) | |
| tree | 22c45646330d05b0ba7c7cf6ab1d556ae8cf44f9 | |
| parent | 50dc8d18f62d58a2330f08fddc069f263d191c90 (diff) | |
| download | lwn-64f6a5d1922bf6d2b2d845de20d4563a6f328e2d.tar.gz lwn-64f6a5d1922bf6d2b2d845de20d4563a6f328e2d.zip | |
container_of: add container_of_const() that preserves const-ness of the pointer
container_of does not preserve the const-ness of a pointer that is
passed into it, which can cause C code that passes in a const pointer to
get a pointer back that is not const and then scribble all over the data
in it. To prevent this, container_of_const() will preserve the const
status of the pointer passed into it using the newly available _Generic()
method.
Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20221205121206.166576-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/container_of.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/container_of.h b/include/linux/container_of.h index 2008e9f4058c..1d898f9158b4 100644 --- a/include/linux/container_of.h +++ b/include/linux/container_of.h @@ -22,4 +22,17 @@ "pointer type mismatch in container_of()"); \ ((type *)(__mptr - offsetof(type, member))); }) +/** + * container_of_const - cast a member of a structure out to the containing + * structure and preserve the const-ness of the pointer + * @ptr: the pointer to the member + * @type: the type of the container struct this is embedded in. + * @member: the name of the member within the struct. + */ +#define container_of_const(ptr, type, member) \ + _Generic(ptr, \ + const typeof(*(ptr)) *: ((const type *)container_of(ptr, type, member)),\ + default: ((type *)container_of(ptr, type, member)) \ + ) + #endif /* _LINUX_CONTAINER_OF_H */ |