/* * Sample dynamic sized record fifo implementation * * Copyright (C) 2010 Stefani Seibold * * Released under the GPL version 2 only. * */ #include #include #include #include #include /* * This module shows how to create a variable sized record fifo. */ /* fifo size in elements (bytes) */ #define FIFO_SIZE 128 /* name of the proc entry */ #define PROC_FIFO "record-fifo" /* lock for procfs read access */ static DEFINE_MUTEX(read_lock); /* lock for procfs write access */ static DEFINE_MUTEX(write_lock); /* * define DYNAMIC in this example for a dynamically allocated fifo. * * Otherwise the fifo storage will be a part of the fifo structure. */ #if 0 #define DYNAMIC #endif /* * struct kfifo_rec_ptr_1 and STRUCT_KFIFO_REC_1 can handle records of a * length between 0 and 255 bytes. * * struct kfifo_rec_ptr_2 and STRUCT_KFIFO_REC_2 can handle records of a * length between 0 and 65535 bytes. */ #ifdef DYNAMIC struct kfifo_rec_ptr_1 test; #else typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest; static mytest test; #endif static const char *expected_result[] = { "a", "bb", "ccc", "dddd", "eeeee", "ffffff", "ggggggg", "hhhhhhhh", "iiiiiiiii", "jjjjjjjjjj", }; static int __init testfunc(void) { char buf[100]; unsigned int i; unsigned int ret; struct { unsigned char buf[6]; } hello = { "hello" }; printk(KERN_INFO "record fifo test start\n"); kfifo_in(&test, &hello, sizeof(hello)); /* show the size of the next record in the fifo */ printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test)); /* put in variable length data */ for (i = 0; i < 10; i++) { memset(buf, 'a' + i, i + 1); kfifo_in(&test, buf, i + 1); } /* skip first element of the fifo */ printk(KERN_INFO "skip 1st element\n"); kfifo_skip(&test); printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test)); /* show the first record without removing from the fifo */ ret = kfifo_out_peek(&test, buf, sizeof(buf)); if (ret) printk(KERN_INFO "%.*s\n", ret, buf); /* check the correctness of all values in the fifo */ i = 0; while (!kfifo_is_empty(&test)) { ret = kfifo_out(&test, buf, sizeof(buf)); buf[ret] = '\0'; printk(KERN_INFO "item = %.*s\n", ret, buf); if (strcmp(buf, expected_result[i++])) { printk(KERN_WARNING "value mismatch: test failed\n"); return -EIO; } } if (i != ARRAY_SIZE(expected_result)) { printk(KERN_WARNING "size mismatch: test failed\n"); return -EIO; } printk(KERN_INFO "test passed\n"); return 0; } static ssize_t fifo_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { int ret; unsigned int copied; if (mutex_lock_interruptible(&write_lock)) return -ERESTARTSYS; ret = kfifo_from_user(&test, buf, count, &copied); mutex_unlock(&write_lock); return ret ? ret : copied; } static ssize_t fifo_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { int ret; unsigned int copied; if (mutex_lock_interruptible(&read_lock)) return -ERESTARTSYS; ret = kfifo_to_user(&test, buf, count, &copied); mutex_unlock(&read_lock); return ret ? ret : copied; } static const struct file_operations fifo_fops = { .owner = THIS_MODULE, .read = fifo_read, .write = fifo_write, .llseek = noop_llseek, }; static int __init example_init(void) { #ifdef DYNAMIC int ret; ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL); if (ret) { printk(KERN_ERR "error kfifo_alloc\n"); return ret; } #else INIT_KFIFO(test); #endif if (testfunc() < 0) { #ifdef DYNAMIC kfifo_free(&test); #endif return -EIO; } if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) { #ifdef DYNAMIC kfifo_free(&test); #endif return -ENOMEM; } return 0; } static void __exit example_exit(void) { remove_proc_entry(PROC_FIFO, NULL); #ifdef DYNAMIC kfifo_free(&test); #endif } module_init(example_init); module_exit(example_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Stefani Seibold "); value='0' selected='selected'>includemode:
authorDaniel Vetter <daniel.vetter@ffwll.ch>2016-12-18 14:35:45 +0100
committerDaniel Vetter <daniel.vetter@ffwll.ch>2017-01-30 10:17:17 +0100
commit4e5b54f127426c82dc2816340c26d951a5bb3429 (patch)
treecc3a8f7e335cf12880bc8d1a1e2066f6cfe0a68e /net/6lowpan/nhc_mobility.c
parent566cf877a1fcb6d6dc0126b076aad062054c2637 (diff)
drm: prevent double-(un)registration for connectors
If we're unlucky then the registration from a hotplugged connector might race with the final registration step on driver load. And since MST topology discover is asynchronous that's even somewhat likely. v2: Also update the kerneldoc for @registered! v3: Review from Chris: - Improve kerneldoc for late_register/early_unregister callbacks. - Use mutex_destroy. Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Sean Paul <seanpaul@chromium.org> Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161218133545.2106-1-daniel.vetter@ffwll.ch (cherry picked from commit e73ab00e9a0f1731f34d0620a9c55f5c30c4ad4e)
Diffstat (limited to 'net/6lowpan/nhc_mobility.c')