1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * fs/eventfd.c 3 * fs/eventfd.c
4 * 4 *
5 * Copyright (C) 2007 Davide Libenzi <davide 5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
6 * 6 *
7 */ 7 */
8 8
9 #include <linux/file.h> 9 #include <linux/file.h>
10 #include <linux/poll.h> 10 #include <linux/poll.h>
11 #include <linux/init.h> 11 #include <linux/init.h>
12 #include <linux/fs.h> 12 #include <linux/fs.h>
13 #include <linux/sched/signal.h> 13 #include <linux/sched/signal.h>
14 #include <linux/kernel.h> 14 #include <linux/kernel.h>
15 #include <linux/slab.h> 15 #include <linux/slab.h>
16 #include <linux/list.h> 16 #include <linux/list.h>
17 #include <linux/spinlock.h> 17 #include <linux/spinlock.h>
18 #include <linux/anon_inodes.h> 18 #include <linux/anon_inodes.h>
19 #include <linux/syscalls.h> 19 #include <linux/syscalls.h>
20 #include <linux/export.h> 20 #include <linux/export.h>
21 #include <linux/kref.h> 21 #include <linux/kref.h>
22 #include <linux/eventfd.h> 22 #include <linux/eventfd.h>
23 #include <linux/proc_fs.h> 23 #include <linux/proc_fs.h>
24 #include <linux/seq_file.h> 24 #include <linux/seq_file.h>
25 #include <linux/idr.h> 25 #include <linux/idr.h>
26 #include <linux/uio.h> 26 #include <linux/uio.h>
27 27
28 static DEFINE_IDA(eventfd_ida); 28 static DEFINE_IDA(eventfd_ida);
29 29
30 struct eventfd_ctx { 30 struct eventfd_ctx {
31 struct kref kref; 31 struct kref kref;
32 wait_queue_head_t wqh; 32 wait_queue_head_t wqh;
33 /* 33 /*
34 * Every time that a write(2) is perfo 34 * Every time that a write(2) is performed on an eventfd, the
35 * value of the __u64 being written is 35 * value of the __u64 being written is added to "count" and a
36 * wakeup is performed on "wqh". If EF 36 * wakeup is performed on "wqh". If EFD_SEMAPHORE flag was not
37 * specified, a read(2) will return th 37 * specified, a read(2) will return the "count" value to userspace,
38 * and will reset "count" to zero. The 38 * and will reset "count" to zero. The kernel side eventfd_signal()
39 * also, adds to the "count" counter a 39 * also, adds to the "count" counter and issue a wakeup.
40 */ 40 */
41 __u64 count; 41 __u64 count;
42 unsigned int flags; 42 unsigned int flags;
43 int id; 43 int id;
44 }; 44 };
45 45
46 /** 46 /**
47 * eventfd_signal_mask - Increment the event c 47 * eventfd_signal_mask - Increment the event counter
48 * @ctx: [in] Pointer to the eventfd context. 48 * @ctx: [in] Pointer to the eventfd context.
49 * @mask: [in] poll mask 49 * @mask: [in] poll mask
50 * 50 *
51 * This function is supposed to be called by t 51 * This function is supposed to be called by the kernel in paths that do not
52 * allow sleeping. In this function we allow t 52 * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
53 * value, and we signal this as overflow condi 53 * value, and we signal this as overflow condition by returning a EPOLLERR
54 * to poll(2). 54 * to poll(2).
55 */ 55 */
56 void eventfd_signal_mask(struct eventfd_ctx *c 56 void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
57 { 57 {
58 unsigned long flags; 58 unsigned long flags;
59 59
60 /* 60 /*
61 * Deadlock or stack overflow issues c 61 * Deadlock or stack overflow issues can happen if we recurse here
62 * through waitqueue wakeup handlers. 62 * through waitqueue wakeup handlers. If the caller users potentially
63 * nested waitqueues with custom wakeu 63 * nested waitqueues with custom wakeup handlers, then it should
64 * check eventfd_signal_allowed() befo 64 * check eventfd_signal_allowed() before calling this function. If
65 * it returns false, the eventfd_signa 65 * it returns false, the eventfd_signal() call should be deferred to a
66 * safe context. 66 * safe context.
67 */ 67 */
68 if (WARN_ON_ONCE(current->in_eventfd)) 68 if (WARN_ON_ONCE(current->in_eventfd))
69 return; 69 return;
70 70
71 spin_lock_irqsave(&ctx->wqh.lock, flag 71 spin_lock_irqsave(&ctx->wqh.lock, flags);
72 current->in_eventfd = 1; 72 current->in_eventfd = 1;
73 if (ctx->count < ULLONG_MAX) 73 if (ctx->count < ULLONG_MAX)
74 ctx->count++; 74 ctx->count++;
75 if (waitqueue_active(&ctx->wqh)) 75 if (waitqueue_active(&ctx->wqh))
76 wake_up_locked_poll(&ctx->wqh, 76 wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
77 current->in_eventfd = 0; 77 current->in_eventfd = 0;
78 spin_unlock_irqrestore(&ctx->wqh.lock, 78 spin_unlock_irqrestore(&ctx->wqh.lock, flags);
79 } 79 }
80 EXPORT_SYMBOL_GPL(eventfd_signal_mask); 80 EXPORT_SYMBOL_GPL(eventfd_signal_mask);
81 81
82 static void eventfd_free_ctx(struct eventfd_ct 82 static void eventfd_free_ctx(struct eventfd_ctx *ctx)
83 { 83 {
84 if (ctx->id >= 0) 84 if (ctx->id >= 0)
85 ida_free(&eventfd_ida, ctx->id 85 ida_free(&eventfd_ida, ctx->id);
86 kfree(ctx); 86 kfree(ctx);
87 } 87 }
88 88
89 static void eventfd_free(struct kref *kref) 89 static void eventfd_free(struct kref *kref)
90 { 90 {
91 struct eventfd_ctx *ctx = container_of 91 struct eventfd_ctx *ctx = container_of(kref, struct eventfd_ctx, kref);
92 92
93 eventfd_free_ctx(ctx); 93 eventfd_free_ctx(ctx);
94 } 94 }
95 95
96 /** 96 /**
97 * eventfd_ctx_put - Releases a reference to t 97 * eventfd_ctx_put - Releases a reference to the internal eventfd context.
98 * @ctx: [in] Pointer to eventfd context. 98 * @ctx: [in] Pointer to eventfd context.
99 * 99 *
100 * The eventfd context reference must have bee 100 * The eventfd context reference must have been previously acquired either
101 * with eventfd_ctx_fdget() or eventfd_ctx_fil 101 * with eventfd_ctx_fdget() or eventfd_ctx_fileget().
102 */ 102 */
103 void eventfd_ctx_put(struct eventfd_ctx *ctx) 103 void eventfd_ctx_put(struct eventfd_ctx *ctx)
104 { 104 {
105 kref_put(&ctx->kref, eventfd_free); 105 kref_put(&ctx->kref, eventfd_free);
106 } 106 }
107 EXPORT_SYMBOL_GPL(eventfd_ctx_put); 107 EXPORT_SYMBOL_GPL(eventfd_ctx_put);
108 108
109 static int eventfd_release(struct inode *inode 109 static int eventfd_release(struct inode *inode, struct file *file)
110 { 110 {
111 struct eventfd_ctx *ctx = file->privat 111 struct eventfd_ctx *ctx = file->private_data;
112 112
113 wake_up_poll(&ctx->wqh, EPOLLHUP); 113 wake_up_poll(&ctx->wqh, EPOLLHUP);
114 eventfd_ctx_put(ctx); 114 eventfd_ctx_put(ctx);
115 return 0; 115 return 0;
116 } 116 }
117 117
118 static __poll_t eventfd_poll(struct file *file 118 static __poll_t eventfd_poll(struct file *file, poll_table *wait)
119 { 119 {
120 struct eventfd_ctx *ctx = file->privat 120 struct eventfd_ctx *ctx = file->private_data;
121 __poll_t events = 0; 121 __poll_t events = 0;
122 u64 count; 122 u64 count;
123 123
124 poll_wait(file, &ctx->wqh, wait); 124 poll_wait(file, &ctx->wqh, wait);
125 125
126 /* 126 /*
127 * All writes to ctx->count occur with 127 * All writes to ctx->count occur within ctx->wqh.lock. This read
128 * can be done outside ctx->wqh.lock b 128 * can be done outside ctx->wqh.lock because we know that poll_wait
129 * takes that lock (through add_wait_q 129 * takes that lock (through add_wait_queue) if our caller will sleep.
130 * 130 *
131 * The read _can_ therefore seep into 131 * The read _can_ therefore seep into add_wait_queue's critical
132 * section, but cannot move above it! 132 * section, but cannot move above it! add_wait_queue's spin_lock acts
133 * as an acquire barrier and ensures t 133 * as an acquire barrier and ensures that the read be ordered properly
134 * against the writes. The following 134 * against the writes. The following CAN happen and is safe:
135 * 135 *
136 * poll 136 * poll write
137 * ----------------- 137 * ----------------- ------------
138 * lock ctx->wqh.lock (in poll_wai 138 * lock ctx->wqh.lock (in poll_wait)
139 * count = ctx->count 139 * count = ctx->count
140 * __add_wait_queue 140 * __add_wait_queue
141 * unlock ctx->wqh.lock 141 * unlock ctx->wqh.lock
142 * 142 * lock ctx->qwh.lock
143 * 143 * ctx->count += n
144 * 144 * if (waitqueue_active)
145 * 145 * wake_up_locked_poll
146 * 146 * unlock ctx->qwh.lock
147 * eventfd_poll returns 0 147 * eventfd_poll returns 0
148 * 148 *
149 * but the following, which would miss 149 * but the following, which would miss a wakeup, cannot happen:
150 * 150 *
151 * poll 151 * poll write
152 * ----------------- 152 * ----------------- ------------
153 * count = ctx->count (INVALID!) 153 * count = ctx->count (INVALID!)
154 * 154 * lock ctx->qwh.lock
155 * 155 * ctx->count += n
156 * 156 * **waitqueue_active is false**
157 * 157 * **no wake_up_locked_poll!**
158 * 158 * unlock ctx->qwh.lock
159 * lock ctx->wqh.lock (in poll_wai 159 * lock ctx->wqh.lock (in poll_wait)
160 * __add_wait_queue 160 * __add_wait_queue
161 * unlock ctx->wqh.lock 161 * unlock ctx->wqh.lock
162 * eventfd_poll returns 0 162 * eventfd_poll returns 0
163 */ 163 */
164 count = READ_ONCE(ctx->count); 164 count = READ_ONCE(ctx->count);
165 165
166 if (count > 0) 166 if (count > 0)
167 events |= EPOLLIN; 167 events |= EPOLLIN;
168 if (count == ULLONG_MAX) 168 if (count == ULLONG_MAX)
169 events |= EPOLLERR; 169 events |= EPOLLERR;
170 if (ULLONG_MAX - 1 > count) 170 if (ULLONG_MAX - 1 > count)
171 events |= EPOLLOUT; 171 events |= EPOLLOUT;
172 172
173 return events; 173 return events;
174 } 174 }
175 175
176 void eventfd_ctx_do_read(struct eventfd_ctx *c 176 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
177 { 177 {
178 lockdep_assert_held(&ctx->wqh.lock); 178 lockdep_assert_held(&ctx->wqh.lock);
179 179
180 *cnt = ((ctx->flags & EFD_SEMAPHORE) & 180 *cnt = ((ctx->flags & EFD_SEMAPHORE) && ctx->count) ? 1 : ctx->count;
181 ctx->count -= *cnt; 181 ctx->count -= *cnt;
182 } 182 }
183 EXPORT_SYMBOL_GPL(eventfd_ctx_do_read); 183 EXPORT_SYMBOL_GPL(eventfd_ctx_do_read);
184 184
185 /** 185 /**
186 * eventfd_ctx_remove_wait_queue - Read the cu 186 * eventfd_ctx_remove_wait_queue - Read the current counter and removes wait queue.
187 * @ctx: [in] Pointer to eventfd context. 187 * @ctx: [in] Pointer to eventfd context.
188 * @wait: [in] Wait queue to be removed. 188 * @wait: [in] Wait queue to be removed.
189 * @cnt: [out] Pointer to the 64-bit counter v 189 * @cnt: [out] Pointer to the 64-bit counter value.
190 * 190 *
191 * Returns %0 if successful, or the following 191 * Returns %0 if successful, or the following error codes:
192 * 192 *
193 * -EAGAIN : The operation would have blo 193 * -EAGAIN : The operation would have blocked.
194 * 194 *
195 * This is used to atomically remove a wait qu 195 * This is used to atomically remove a wait queue entry from the eventfd wait
196 * queue head, and read/reset the counter valu 196 * queue head, and read/reset the counter value.
197 */ 197 */
198 int eventfd_ctx_remove_wait_queue(struct event 198 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
199 __u64 *cnt) 199 __u64 *cnt)
200 { 200 {
201 unsigned long flags; 201 unsigned long flags;
202 202
203 spin_lock_irqsave(&ctx->wqh.lock, flag 203 spin_lock_irqsave(&ctx->wqh.lock, flags);
204 eventfd_ctx_do_read(ctx, cnt); 204 eventfd_ctx_do_read(ctx, cnt);
205 __remove_wait_queue(&ctx->wqh, wait); 205 __remove_wait_queue(&ctx->wqh, wait);
206 if (*cnt != 0 && waitqueue_active(&ctx 206 if (*cnt != 0 && waitqueue_active(&ctx->wqh))
207 wake_up_locked_poll(&ctx->wqh, 207 wake_up_locked_poll(&ctx->wqh, EPOLLOUT);
208 spin_unlock_irqrestore(&ctx->wqh.lock, 208 spin_unlock_irqrestore(&ctx->wqh.lock, flags);
209 209
210 return *cnt != 0 ? 0 : -EAGAIN; 210 return *cnt != 0 ? 0 : -EAGAIN;
211 } 211 }
212 EXPORT_SYMBOL_GPL(eventfd_ctx_remove_wait_queu 212 EXPORT_SYMBOL_GPL(eventfd_ctx_remove_wait_queue);
213 213
214 static ssize_t eventfd_read(struct kiocb *iocb 214 static ssize_t eventfd_read(struct kiocb *iocb, struct iov_iter *to)
215 { 215 {
216 struct file *file = iocb->ki_filp; 216 struct file *file = iocb->ki_filp;
217 struct eventfd_ctx *ctx = file->privat 217 struct eventfd_ctx *ctx = file->private_data;
218 __u64 ucnt = 0; 218 __u64 ucnt = 0;
219 219
220 if (iov_iter_count(to) < sizeof(ucnt)) 220 if (iov_iter_count(to) < sizeof(ucnt))
221 return -EINVAL; 221 return -EINVAL;
222 spin_lock_irq(&ctx->wqh.lock); 222 spin_lock_irq(&ctx->wqh.lock);
223 if (!ctx->count) { 223 if (!ctx->count) {
224 if ((file->f_flags & O_NONBLOC 224 if ((file->f_flags & O_NONBLOCK) ||
225 (iocb->ki_flags & IOCB_NOW 225 (iocb->ki_flags & IOCB_NOWAIT)) {
226 spin_unlock_irq(&ctx-> 226 spin_unlock_irq(&ctx->wqh.lock);
227 return -EAGAIN; 227 return -EAGAIN;
228 } 228 }
229 229
230 if (wait_event_interruptible_l 230 if (wait_event_interruptible_locked_irq(ctx->wqh, ctx->count)) {
231 spin_unlock_irq(&ctx-> 231 spin_unlock_irq(&ctx->wqh.lock);
232 return -ERESTARTSYS; 232 return -ERESTARTSYS;
233 } 233 }
234 } 234 }
235 eventfd_ctx_do_read(ctx, &ucnt); 235 eventfd_ctx_do_read(ctx, &ucnt);
236 current->in_eventfd = 1; 236 current->in_eventfd = 1;
237 if (waitqueue_active(&ctx->wqh)) 237 if (waitqueue_active(&ctx->wqh))
238 wake_up_locked_poll(&ctx->wqh, 238 wake_up_locked_poll(&ctx->wqh, EPOLLOUT);
239 current->in_eventfd = 0; 239 current->in_eventfd = 0;
240 spin_unlock_irq(&ctx->wqh.lock); 240 spin_unlock_irq(&ctx->wqh.lock);
241 if (unlikely(copy_to_iter(&ucnt, sizeo 241 if (unlikely(copy_to_iter(&ucnt, sizeof(ucnt), to) != sizeof(ucnt)))
242 return -EFAULT; 242 return -EFAULT;
243 243
244 return sizeof(ucnt); 244 return sizeof(ucnt);
245 } 245 }
246 246
247 static ssize_t eventfd_write(struct file *file 247 static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t count,
248 loff_t *ppos) 248 loff_t *ppos)
249 { 249 {
250 struct eventfd_ctx *ctx = file->privat 250 struct eventfd_ctx *ctx = file->private_data;
251 ssize_t res; 251 ssize_t res;
252 __u64 ucnt; 252 __u64 ucnt;
253 253
254 if (count != sizeof(ucnt)) 254 if (count != sizeof(ucnt))
255 return -EINVAL; 255 return -EINVAL;
256 if (copy_from_user(&ucnt, buf, sizeof( 256 if (copy_from_user(&ucnt, buf, sizeof(ucnt)))
257 return -EFAULT; 257 return -EFAULT;
258 if (ucnt == ULLONG_MAX) 258 if (ucnt == ULLONG_MAX)
259 return -EINVAL; 259 return -EINVAL;
260 spin_lock_irq(&ctx->wqh.lock); 260 spin_lock_irq(&ctx->wqh.lock);
261 res = -EAGAIN; 261 res = -EAGAIN;
262 if (ULLONG_MAX - ctx->count > ucnt) 262 if (ULLONG_MAX - ctx->count > ucnt)
263 res = sizeof(ucnt); 263 res = sizeof(ucnt);
264 else if (!(file->f_flags & O_NONBLOCK) 264 else if (!(file->f_flags & O_NONBLOCK)) {
265 res = wait_event_interruptible 265 res = wait_event_interruptible_locked_irq(ctx->wqh,
266 ULLONG_MAX - c 266 ULLONG_MAX - ctx->count > ucnt);
267 if (!res) 267 if (!res)
268 res = sizeof(ucnt); 268 res = sizeof(ucnt);
269 } 269 }
270 if (likely(res > 0)) { 270 if (likely(res > 0)) {
271 ctx->count += ucnt; 271 ctx->count += ucnt;
272 current->in_eventfd = 1; 272 current->in_eventfd = 1;
273 if (waitqueue_active(&ctx->wqh 273 if (waitqueue_active(&ctx->wqh))
274 wake_up_locked_poll(&c 274 wake_up_locked_poll(&ctx->wqh, EPOLLIN);
275 current->in_eventfd = 0; 275 current->in_eventfd = 0;
276 } 276 }
277 spin_unlock_irq(&ctx->wqh.lock); 277 spin_unlock_irq(&ctx->wqh.lock);
278 278
279 return res; 279 return res;
280 } 280 }
281 281
282 #ifdef CONFIG_PROC_FS 282 #ifdef CONFIG_PROC_FS
283 static void eventfd_show_fdinfo(struct seq_fil 283 static void eventfd_show_fdinfo(struct seq_file *m, struct file *f)
284 { 284 {
285 struct eventfd_ctx *ctx = f->private_d 285 struct eventfd_ctx *ctx = f->private_data;
286 __u64 cnt; 286 __u64 cnt;
287 287
288 spin_lock_irq(&ctx->wqh.lock); 288 spin_lock_irq(&ctx->wqh.lock);
289 cnt = ctx->count; 289 cnt = ctx->count;
290 spin_unlock_irq(&ctx->wqh.lock); 290 spin_unlock_irq(&ctx->wqh.lock);
291 291
292 seq_printf(m, 292 seq_printf(m,
293 "eventfd-count: %16llx\n" 293 "eventfd-count: %16llx\n"
294 "eventfd-id: %d\n" 294 "eventfd-id: %d\n"
295 "eventfd-semaphore: %d\n", 295 "eventfd-semaphore: %d\n",
296 cnt, 296 cnt,
297 ctx->id, 297 ctx->id,
298 !!(ctx->flags & EFD_SEMAPHO 298 !!(ctx->flags & EFD_SEMAPHORE));
299 } 299 }
300 #endif 300 #endif
301 301
302 static const struct file_operations eventfd_fo 302 static const struct file_operations eventfd_fops = {
303 #ifdef CONFIG_PROC_FS 303 #ifdef CONFIG_PROC_FS
304 .show_fdinfo = eventfd_show_fdinfo, 304 .show_fdinfo = eventfd_show_fdinfo,
305 #endif 305 #endif
306 .release = eventfd_release, 306 .release = eventfd_release,
307 .poll = eventfd_poll, 307 .poll = eventfd_poll,
308 .read_iter = eventfd_read, 308 .read_iter = eventfd_read,
309 .write = eventfd_write, 309 .write = eventfd_write,
310 .llseek = noop_llseek, 310 .llseek = noop_llseek,
311 }; 311 };
312 312
313 /** 313 /**
314 * eventfd_fget - Acquire a reference of an ev 314 * eventfd_fget - Acquire a reference of an eventfd file descriptor.
315 * @fd: [in] Eventfd file descriptor. 315 * @fd: [in] Eventfd file descriptor.
316 * 316 *
317 * Returns a pointer to the eventfd file struc 317 * Returns a pointer to the eventfd file structure in case of success, or the
318 * following error pointer: 318 * following error pointer:
319 * 319 *
320 * -EBADF : Invalid @fd file descriptor. 320 * -EBADF : Invalid @fd file descriptor.
321 * -EINVAL : The @fd file descriptor is not 321 * -EINVAL : The @fd file descriptor is not an eventfd file.
322 */ 322 */
323 struct file *eventfd_fget(int fd) 323 struct file *eventfd_fget(int fd)
324 { 324 {
325 struct file *file; 325 struct file *file;
326 326
327 file = fget(fd); 327 file = fget(fd);
328 if (!file) 328 if (!file)
329 return ERR_PTR(-EBADF); 329 return ERR_PTR(-EBADF);
330 if (file->f_op != &eventfd_fops) { 330 if (file->f_op != &eventfd_fops) {
331 fput(file); 331 fput(file);
332 return ERR_PTR(-EINVAL); 332 return ERR_PTR(-EINVAL);
333 } 333 }
334 334
335 return file; 335 return file;
336 } 336 }
337 EXPORT_SYMBOL_GPL(eventfd_fget); 337 EXPORT_SYMBOL_GPL(eventfd_fget);
338 338
339 /** 339 /**
340 * eventfd_ctx_fdget - Acquires a reference to 340 * eventfd_ctx_fdget - Acquires a reference to the internal eventfd context.
341 * @fd: [in] Eventfd file descriptor. 341 * @fd: [in] Eventfd file descriptor.
342 * 342 *
343 * Returns a pointer to the internal eventfd c 343 * Returns a pointer to the internal eventfd context, otherwise the error
344 * pointers returned by the following function 344 * pointers returned by the following functions:
345 * 345 *
346 * eventfd_fget 346 * eventfd_fget
347 */ 347 */
348 struct eventfd_ctx *eventfd_ctx_fdget(int fd) 348 struct eventfd_ctx *eventfd_ctx_fdget(int fd)
349 { 349 {
350 struct eventfd_ctx *ctx; 350 struct eventfd_ctx *ctx;
351 struct fd f = fdget(fd); 351 struct fd f = fdget(fd);
352 if (!f.file) 352 if (!f.file)
353 return ERR_PTR(-EBADF); 353 return ERR_PTR(-EBADF);
354 ctx = eventfd_ctx_fileget(f.file); 354 ctx = eventfd_ctx_fileget(f.file);
355 fdput(f); 355 fdput(f);
356 return ctx; 356 return ctx;
357 } 357 }
358 EXPORT_SYMBOL_GPL(eventfd_ctx_fdget); 358 EXPORT_SYMBOL_GPL(eventfd_ctx_fdget);
359 359
360 /** 360 /**
361 * eventfd_ctx_fileget - Acquires a reference 361 * eventfd_ctx_fileget - Acquires a reference to the internal eventfd context.
362 * @file: [in] Eventfd file pointer. 362 * @file: [in] Eventfd file pointer.
363 * 363 *
364 * Returns a pointer to the internal eventfd c 364 * Returns a pointer to the internal eventfd context, otherwise the error
365 * pointer: 365 * pointer:
366 * 366 *
367 * -EINVAL : The @fd file descriptor is not 367 * -EINVAL : The @fd file descriptor is not an eventfd file.
368 */ 368 */
369 struct eventfd_ctx *eventfd_ctx_fileget(struct 369 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file)
370 { 370 {
371 struct eventfd_ctx *ctx; 371 struct eventfd_ctx *ctx;
372 372
373 if (file->f_op != &eventfd_fops) 373 if (file->f_op != &eventfd_fops)
374 return ERR_PTR(-EINVAL); 374 return ERR_PTR(-EINVAL);
375 375
376 ctx = file->private_data; 376 ctx = file->private_data;
377 kref_get(&ctx->kref); 377 kref_get(&ctx->kref);
378 return ctx; 378 return ctx;
379 } 379 }
380 EXPORT_SYMBOL_GPL(eventfd_ctx_fileget); 380 EXPORT_SYMBOL_GPL(eventfd_ctx_fileget);
381 381
382 static int do_eventfd(unsigned int count, int 382 static int do_eventfd(unsigned int count, int flags)
383 { 383 {
384 struct eventfd_ctx *ctx; 384 struct eventfd_ctx *ctx;
385 struct file *file; 385 struct file *file;
386 int fd; 386 int fd;
387 387
388 /* Check the EFD_* constants for consi 388 /* Check the EFD_* constants for consistency. */
389 BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC) 389 BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC);
390 BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOC 390 BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK);
391 BUILD_BUG_ON(EFD_SEMAPHORE != (1 << 0) 391 BUILD_BUG_ON(EFD_SEMAPHORE != (1 << 0));
392 392
393 if (flags & ~EFD_FLAGS_SET) 393 if (flags & ~EFD_FLAGS_SET)
394 return -EINVAL; 394 return -EINVAL;
395 395
396 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL 396 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
397 if (!ctx) 397 if (!ctx)
398 return -ENOMEM; 398 return -ENOMEM;
399 399
400 kref_init(&ctx->kref); 400 kref_init(&ctx->kref);
401 init_waitqueue_head(&ctx->wqh); 401 init_waitqueue_head(&ctx->wqh);
402 ctx->count = count; 402 ctx->count = count;
403 ctx->flags = flags; 403 ctx->flags = flags;
404 ctx->id = ida_alloc(&eventfd_ida, GFP_ 404 ctx->id = ida_alloc(&eventfd_ida, GFP_KERNEL);
405 405
406 flags &= EFD_SHARED_FCNTL_FLAGS; 406 flags &= EFD_SHARED_FCNTL_FLAGS;
407 flags |= O_RDWR; 407 flags |= O_RDWR;
408 fd = get_unused_fd_flags(flags); 408 fd = get_unused_fd_flags(flags);
409 if (fd < 0) 409 if (fd < 0)
410 goto err; 410 goto err;
411 411
412 file = anon_inode_getfile("[eventfd]", 412 file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx, flags);
413 if (IS_ERR(file)) { 413 if (IS_ERR(file)) {
414 put_unused_fd(fd); 414 put_unused_fd(fd);
415 fd = PTR_ERR(file); 415 fd = PTR_ERR(file);
416 goto err; 416 goto err;
417 } 417 }
418 418
419 file->f_mode |= FMODE_NOWAIT; 419 file->f_mode |= FMODE_NOWAIT;
420 fd_install(fd, file); 420 fd_install(fd, file);
421 return fd; 421 return fd;
422 err: 422 err:
423 eventfd_free_ctx(ctx); 423 eventfd_free_ctx(ctx);
424 return fd; 424 return fd;
425 } 425 }
426 426
427 SYSCALL_DEFINE2(eventfd2, unsigned int, count, 427 SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags)
428 { 428 {
429 return do_eventfd(count, flags); 429 return do_eventfd(count, flags);
430 } 430 }
431 431
432 SYSCALL_DEFINE1(eventfd, unsigned int, count) 432 SYSCALL_DEFINE1(eventfd, unsigned int, count)
433 { 433 {
434 return do_eventfd(count, 0); 434 return do_eventfd(count, 0);
435 } 435 }
436 436
437 437
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