summaryrefslogtreecommitdiff
path: root/scripts/coccinelle/api/stream_open.cocci
blob: df00d6619b0623f1e904531e064496f96eb62fc0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
// SPDX-License-Identifier: GPL-2.0
// Author: Kirill Smelkov (kirr@nexedi.com)
//
// Search for stream-like files that are using nonseekable_open and convert
// them to stream_open. A stream-like file is a file that does not use ppos in
// its read and write. Rationale for the conversion is to avoid deadlock in
// between read and write.

virtual report
virtual patch
virtual explain  // explain decisions in the patch (SPFLAGS="-D explain")

// stream-like reader & writer - ones that do not depend on f_pos.
@ stream_reader @
identifier readstream, ppos;
identifier f, buf, len;
type loff_t;
@@
  ssize_t readstream(struct file *f, char *buf, size_t len, loff_t *ppos)
  {
    ... when != ppos
  }

@ stream_writer @
identifier writestream, ppos;
identifier f, buf, len;
type loff_t;
@@
  ssize_t writestream(struct file *f, const char *buf, size_t len, loff_t *ppos)
  {
    ... when != ppos
  }


// a function that blocks
@ blocks @
identifier block_f;
identifier wait =~ "^wait_.*";
@@
  block_f(...) {
    ... when exists
    wait(...)
    ... when exists
  }

// stream_reader that can block inside.
//
// XXX wait_* can be called not directly from current function (e.g. func -> f -> g -> wait())
// XXX currently reader_blocks supports only direct and 1-level indirect cases.
@ reader_blocks_direct @
identifier stream_reader.readstream;
identifier wait =~ "^wait_.*";
@@
  readstream(...)
  {
    ... when exists
    wait(...)
    ... when exists
  }

@ reader_blocks_1 @
identifier stream_reader.readstream;
identifier blocks.block_f;
@@
  readstream(...)
  {
    ... when exists
    block_f(...)
    ... when exists
  }

@ reader_blocks depends on reader_blocks_direct || reader_blocks_1 @
identifier stream_reader.readstream;
@@
  readstream(...) {
    ...
  }


// file_operations + whether they have _any_ .read, .write, .llseek ... at all.
//
// XXX add support for file_operations xxx[N] = ...	(sound/core/pcm_native.c)
@ fops0 @
identifier fops;
@@
  struct file_operations fops = {
    ...
  };

@ has_read @
identifier fops0.fops;
identifier read_f;
@@
  struct file_operations fops = {
    .read = read_f,
  };

@ has_read_iter @
identifier fops0.fops;
identifier read_iter_f;
@@
  struct file_operations fops = {
    .read_iter = read_iter_f,
  };

@ has_write @
identifier fops0.fops;
identifier write_f;
@@
  struct file_operations fops = {
    .write = write_f,
  };

@ has_write_iter @
identifier fops0.fops;
identifier write_iter_f;
@@
  struct file_operations fops = {
    .write_iter = write_iter_f,
  };

@ has_llseek @
identifier fops0.fops;
identifier llseek_f;
@@
  struct file_operations fops = {
    .llseek = llseek_f,
  };

@ has_no_llseek @
identifier fops0.fops;
@@
  struct file_operations fops = {
    .llseek = no_llseek,
  };

@ has_noop_llseek @
identifier fops0.fops;
@@
  struct file_operations fops = {
    .llseek = noop_llseek,
  };

@ has_mmap @
identifier fops0.fops;
identifier mmap_f;
@@
  struct file_operations fops = {
    .mmap = mmap_f,
  };

@ has_copy_file_range @
identifier fops0.fops;
identifier copy_file_range_f;
@@
  struct file_operations fops = {
    .copy_file_range = copy_file_range_f,
  };

@ has_remap_file_range @
identifier fops0.fops;
identifier remap_file_range_f;
@@
  struct file_operations fops = {
    .remap_file_range = remap_file_range_f,
  };

@ has_splice_read @
identifier fops0.fops;
identifier splice_read_f;
@@
  struct file_operations fops = {
    .splice_read = splice_read_f,
  };

@ has_splice_write @
identifier fops0.fops;
identifier splice_write_f;
@@
  struct file_operations fops = {
    .splice_write = splice_write_f,
  };


// file_operations that is candidate for stream_open conversion - it does not
// use mmap and other methods that assume @offset access to file.
//
// XXX for simplicity require no .{read/write}_iter and no .splice_{read/write} for now.
// XXX maybe_steam.fops cannot be used in other rules - it gives "bad rule maybe_stream or bad variable fops".
@ maybe_stream depends on (!has_llseek || has_no_llseek || has_noop_llseek) && !has_mmap && !has_copy_file_range && !has_remap_file_range && !has_read_iter && !has_write_iter && !has_splice_read && !has_splice_write @
identifier fops0.fops;
@@
  struct file_operations fops = {
  };


// ---- conversions ----

// XXX .open = nonseekable_open -> .open = stream_open
// XXX .open = func -> openfunc -> nonseekable_open

// read & write
//
// if both are used in the same file_operations together with an opener -
// under that conditions we can use stream_open instead of nonseekable_open.
@ fops_rw depends on maybe_stream @
identifier fops0.fops, openfunc;
identifier stream_reader.readstream;
identifier stream_writer.writestream;
@@
  struct file_operations fops = {
      .open  = openfunc,
      .read  = readstream,
      .write = writestream,
  };

@ report_rw depends on report @
identifier fops_rw.openfunc;
position p1;
@@
  openfunc(...) {
    <...
     nonseekable_open@p1
    ...>
  }

@ script:python depends on report && reader_blocks @
fops << fops0.fops;
p << report_rw.p1;
@@
coccilib.report.print_report(p[0],
  "ERROR: %s: .read() can deadlock .write(); change nonseekable_open -> stream_open to fix." % (fops,))

@ script:python depends on report && !reader_blocks @
fops << fops0.fops;
p << report_rw.p1;
@@
coccilib.report.print_report(p[0],
  "WARNING: %s: .read() and .write() have stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))


@ explain_rw_deadlocked depends on explain && reader_blocks @
identifier fops_rw.openfunc;
@@
  openfunc(...) {
    <...
-    nonseekable_open
+    nonseekable_open /* read & write (was deadlock) */
    ...>
  }


@ explain_rw_nodeadlock depends on explain && !reader_blocks @
identifier fops_rw.openfunc;
@@
  openfunc(...) {
    <...
-    nonseekable_open
+    nonseekable_open /* read & write (no direct deadlock) */
    ...>
  }

@ patch_rw depends on patch @
identifier fops_rw.openfunc;
@@
  openfunc(...) {
    <...
-   nonseekable_open
+   stream_open
    ...>
  }


// read, but not write
@ fops_r depends on maybe_stream && !has_write @
identifier fops0.fops, openfunc;
identifier stream_reader.readstream;
@@
  struct file_operations fops = {
      .open  = openfunc,
      .read  = readstream,
  };

@ report_r depends on report @
identifier fops_r.openfunc;
position p1;
@@
  openfunc(...) {
    <...
    nonseekable_open@p1
    ...>
  }

@ script:python depends on report @
fops << fops0.fops;
p << report_r.p1;
@@
coccilib.report.print_report(p[0],
  "WARNING: %s: .read() has stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))

@ explain_r depends on explain @
identifier fops_r.openfunc;
@@
  openfunc(...) {
    <...
-   nonseekable_open
+   nonseekable_open /* read only */
    ...>
  }

@ patch_r depends on patch @
identifier fops_r.openfunc;
@@
  openfunc(...) {
    <...
-   nonseekable_open
+   stream_open
    ...>
  }


// write, but not read
@ fops_w depends on maybe_stream && !has_read @
identifier fops0.fops, openfunc;
identifier stream_writer.writestream;
@@
  struct file_operations fops = {
      .open  = openfunc,
      .write = writestream,
  };

@ report_w depends on report @
identifier fops_w.openfunc;
position p1;
@@
  openfunc(...) {
    <...
    nonseekable_open@p1
    ...>
  }

@ script:python depends on report @
fops << fops0.fops;
p << report_w.p1;
@@
coccilib.report.print_report(p[0],
  "WARNING: %s: .write() has stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))

@ explain_w depends on explain @
identifier fops_w.openfunc;
@@
  openfunc(...) {
    <...
-   nonseekable_open
+   nonseekable_open /* write only */
    ...>
  }

@ patch_w depends on patch @
identifier fops_w.openfunc;
@@
  openfunc(...) {
    <...
-   nonseekable_open
+   stream_open
    ...>
  }


// no read, no write - don't change anything