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| author | Dave Airlie <airlied@redhat.com> | 2026-09-26 07:57:59 +1000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2026-09-26 07:58:24 +1000 |
| commit | a9ed3aa9b87ee41e8ab3ff471b1331c154767e45 (patch) | |
| tree | cc62d74e0eb4905246978674461e78e2f9df2afd /Documentation/userspace-api/ioctl/ioctl-decoding.rst | |
| download | linux-stable-a9ed3aa9b87ee41e8ab3ff471b1331c154767e45.tar.gz linux-stable-a9ed3aa9b87ee41e8ab3ff471b1331c154767e45.zip | |
Merge tag 'drm-misc-fixes-2026-09-24' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-fixesgrafted
A number of fixes:
- bridge:
- samsung-dsim: fix GPIO lifetime
- client: Null pointer dereference fix
- imagination: error handling fix, page handling fix
- nouveau: fix reference leaks, double-frees, out-of-bounds accesses,
use-after-frees, don't reject config without SCDC, a number of
workarounds
- virtio: fix memory leak, reference leaks, null pointer dereference,
add pixel blend mode, cache coherency fix
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Maxime Ripard <self@mripard.dev>
Link: https://patch.msgid.link/arU22zzqUGDEco1y@houat
Diffstat (limited to 'Documentation/userspace-api/ioctl/ioctl-decoding.rst')
| -rw-r--r-- | Documentation/userspace-api/ioctl/ioctl-decoding.rst | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/userspace-api/ioctl/ioctl-decoding.rst b/Documentation/userspace-api/ioctl/ioctl-decoding.rst new file mode 100644 index 000000000..380d6bb3e --- /dev/null +++ b/Documentation/userspace-api/ioctl/ioctl-decoding.rst @@ -0,0 +1,31 @@ +============================== +Decoding an IOCTL Magic Number +============================== + +To decode a hex IOCTL code: + +Most architectures use this generic format, but check +include/ARCH/ioctl.h for specifics, e.g. powerpc +uses 3 bits to encode read/write and 13 bits for size. + + ====== ================================== + bits meaning + ====== ================================== + 31-30 00 - no parameters: uses _IO macro + 10 - read: _IOR + 01 - write: _IOW + 11 - read/write: _IOWR + + 29-16 size of arguments + + 15-8 ascii character supposedly + unique to each driver + + 7-0 function # + ====== ================================== + + +So for example 0x82187201 is a read with arg length of 0x218, +character 'r' function 1. Grepping the source reveals this is:: + + #define VFAT_IOCTL_READDIR_BOTH _IOR('r', 1, struct dirent [2]) |
