Hi Rob,
On 28 June 2018 at 13:52, Robert Foss robert.foss@collabora.com wrote:
Hey Emil,
On 2018-06-25 19:36, Emil Velikov wrote:
From: Emil Velikov emil.velikov@collabora.com
Currently we dynamically allocate 16 pointers and reallocate more as needed.
Instead, allocate the maximum number (256) on stack - the number is small enough and is unlikely to change in the foreseeable future.
This allows us to simplify the error handling and even shed a few bytes off the final binary.
Signed-off-by: Emil Velikov emil.velikov@collabora.com
xf86drm.c | 64 ++++++------------------------------------------------- 1 file changed, 6 insertions(+), 58 deletions(-)
diff --git a/xf86drm.c b/xf86drm.c index 114cf855..d4810740 100644 --- a/xf86drm.c +++ b/xf86drm.c @@ -3846,7 +3846,7 @@ int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device) return 0; #else
- drmDevicePtr *local_devices;
- drmDevicePtr local_devices[256];
This number is seen later on in this patch, maybe it should be broken out into a define, since it's reused later on too at [1].
Sure thing. The lame MAX_DRM_NODES comes to mind, so alternatives are welcome.
drmDevicePtr d; DIR *sysdir; struct dirent *dent;@@ -3854,7 +3854,6 @@ int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device) int subsystem_type; int maj, min; int ret, i, node_count;
- int max_count = 16; dev_t find_rdev; if (drm_device_validate_flags(flags))
@@ -3877,15 +3876,9 @@ int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device) if (subsystem_type < 0) return subsystem_type;
- local_devices = calloc(max_count, sizeof(drmDevicePtr));
- if (local_devices == NULL)
return -ENOMEM;sysdir = opendir(DRM_DIR_NAME);- if (!sysdir) {
ret = -errno;goto free_locals;- }
- if (!sysdir)
return -errno; i = 0; while ((dent = readdir(sysdir))) {@@ -3893,16 +3886,6 @@ int drmGetDevice2(int fd, uint32_t flags, drmDevicePtr *device) if (ret) continue;
if (i >= max_count) {Is this check really not needded what exactly is it that defines 256 as the maximum?
From what I understand readdir(sysdir) is the call that defines how many devices will be looked through, and as far as I understand it can return an arbitrary number of files.
The kernel drm core has a number of places that assume maximum of 3x64 devices nodes. That's 64 for each of primary, control and render nodes. I've rounded it up to 256 for simplicity.
I assume we'll be able to see if anyone changes the kernel, although bailing out just in case is a good idea. The is one exciting error message - let me know if anything else comes to mind.
if (i >= MAX_DRM_NODES) { fprintf(stderr, "More than %d drm nodes detected. Please report a bug - that should not happen.\nSkipping extra nodes\n", MAX_DRM_NODES); break; }
I'll send out v2 for the patches that need work some time tomorrow/over the weekend..
Thanks Emil