0001 // SPDX-License-Identifier: GPL-2.0
0002 // Author: Kirill Smelkov (kirr@nexedi.com)
0003 //
0004 // Search for stream-like files that are using nonseekable_open and convert
0005 // them to stream_open. A stream-like file is a file that does not use ppos in
0006 // its read and write. Rationale for the conversion is to avoid deadlock in
0007 // between read and write.
0008
0009 virtual report
0010 virtual patch
0011 virtual explain // explain decisions in the patch (SPFLAGS="-D explain")
0012
0013 // stream-like reader & writer - ones that do not depend on f_pos.
0014 @ stream_reader @
0015 identifier readstream, ppos;
0016 identifier f, buf, len;
0017 type loff_t;
0018 @@
0019 ssize_t readstream(struct file *f, char *buf, size_t len, loff_t *ppos)
0020 {
0021 ... when != ppos
0022 }
0023
0024 @ stream_writer @
0025 identifier writestream, ppos;
0026 identifier f, buf, len;
0027 type loff_t;
0028 @@
0029 ssize_t writestream(struct file *f, const char *buf, size_t len, loff_t *ppos)
0030 {
0031 ... when != ppos
0032 }
0033
0034
0035 // a function that blocks
0036 @ blocks @
0037 identifier block_f;
0038 identifier wait =~ "^wait_.*";
0039 @@
0040 block_f(...) {
0041 ... when exists
0042 wait(...)
0043 ... when exists
0044 }
0045
0046 // stream_reader that can block inside.
0047 //
0048 // XXX wait_* can be called not directly from current function (e.g. func -> f -> g -> wait())
0049 // XXX currently reader_blocks supports only direct and 1-level indirect cases.
0050 @ reader_blocks_direct @
0051 identifier stream_reader.readstream;
0052 identifier wait =~ "^wait_.*";
0053 @@
0054 readstream(...)
0055 {
0056 ... when exists
0057 wait(...)
0058 ... when exists
0059 }
0060
0061 @ reader_blocks_1 @
0062 identifier stream_reader.readstream;
0063 identifier blocks.block_f;
0064 @@
0065 readstream(...)
0066 {
0067 ... when exists
0068 block_f(...)
0069 ... when exists
0070 }
0071
0072 @ reader_blocks depends on reader_blocks_direct || reader_blocks_1 @
0073 identifier stream_reader.readstream;
0074 @@
0075 readstream(...) {
0076 ...
0077 }
0078
0079
0080 // file_operations + whether they have _any_ .read, .write, .llseek ... at all.
0081 //
0082 // XXX add support for file_operations xxx[N] = ... (sound/core/pcm_native.c)
0083 @ fops0 @
0084 identifier fops;
0085 @@
0086 struct file_operations fops = {
0087 ...
0088 };
0089
0090 @ has_read @
0091 identifier fops0.fops;
0092 identifier read_f;
0093 @@
0094 struct file_operations fops = {
0095 .read = read_f,
0096 };
0097
0098 @ has_read_iter @
0099 identifier fops0.fops;
0100 identifier read_iter_f;
0101 @@
0102 struct file_operations fops = {
0103 .read_iter = read_iter_f,
0104 };
0105
0106 @ has_write @
0107 identifier fops0.fops;
0108 identifier write_f;
0109 @@
0110 struct file_operations fops = {
0111 .write = write_f,
0112 };
0113
0114 @ has_write_iter @
0115 identifier fops0.fops;
0116 identifier write_iter_f;
0117 @@
0118 struct file_operations fops = {
0119 .write_iter = write_iter_f,
0120 };
0121
0122 @ has_llseek @
0123 identifier fops0.fops;
0124 identifier llseek_f;
0125 @@
0126 struct file_operations fops = {
0127 .llseek = llseek_f,
0128 };
0129
0130 @ has_no_llseek @
0131 identifier fops0.fops;
0132 @@
0133 struct file_operations fops = {
0134 .llseek = no_llseek,
0135 };
0136
0137 @ has_noop_llseek @
0138 identifier fops0.fops;
0139 @@
0140 struct file_operations fops = {
0141 .llseek = noop_llseek,
0142 };
0143
0144 @ has_mmap @
0145 identifier fops0.fops;
0146 identifier mmap_f;
0147 @@
0148 struct file_operations fops = {
0149 .mmap = mmap_f,
0150 };
0151
0152 @ has_copy_file_range @
0153 identifier fops0.fops;
0154 identifier copy_file_range_f;
0155 @@
0156 struct file_operations fops = {
0157 .copy_file_range = copy_file_range_f,
0158 };
0159
0160 @ has_remap_file_range @
0161 identifier fops0.fops;
0162 identifier remap_file_range_f;
0163 @@
0164 struct file_operations fops = {
0165 .remap_file_range = remap_file_range_f,
0166 };
0167
0168 @ has_splice_read @
0169 identifier fops0.fops;
0170 identifier splice_read_f;
0171 @@
0172 struct file_operations fops = {
0173 .splice_read = splice_read_f,
0174 };
0175
0176 @ has_splice_write @
0177 identifier fops0.fops;
0178 identifier splice_write_f;
0179 @@
0180 struct file_operations fops = {
0181 .splice_write = splice_write_f,
0182 };
0183
0184
0185 // file_operations that is candidate for stream_open conversion - it does not
0186 // use mmap and other methods that assume @offset access to file.
0187 //
0188 // XXX for simplicity require no .{read/write}_iter and no .splice_{read/write} for now.
0189 // XXX maybe_steam.fops cannot be used in other rules - it gives "bad rule maybe_stream or bad variable fops".
0190 @ 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 @
0191 identifier fops0.fops;
0192 @@
0193 struct file_operations fops = {
0194 };
0195
0196
0197 // ---- conversions ----
0198
0199 // XXX .open = nonseekable_open -> .open = stream_open
0200 // XXX .open = func -> openfunc -> nonseekable_open
0201
0202 // read & write
0203 //
0204 // if both are used in the same file_operations together with an opener -
0205 // under that conditions we can use stream_open instead of nonseekable_open.
0206 @ fops_rw depends on maybe_stream @
0207 identifier fops0.fops, openfunc;
0208 identifier stream_reader.readstream;
0209 identifier stream_writer.writestream;
0210 @@
0211 struct file_operations fops = {
0212 .open = openfunc,
0213 .read = readstream,
0214 .write = writestream,
0215 };
0216
0217 @ report_rw depends on report @
0218 identifier fops_rw.openfunc;
0219 position p1;
0220 @@
0221 openfunc(...) {
0222 <...
0223 nonseekable_open@p1
0224 ...>
0225 }
0226
0227 @ script:python depends on report && reader_blocks @
0228 fops << fops0.fops;
0229 p << report_rw.p1;
0230 @@
0231 coccilib.report.print_report(p[0],
0232 "ERROR: %s: .read() can deadlock .write(); change nonseekable_open -> stream_open to fix." % (fops,))
0233
0234 @ script:python depends on report && !reader_blocks @
0235 fops << fops0.fops;
0236 p << report_rw.p1;
0237 @@
0238 coccilib.report.print_report(p[0],
0239 "WARNING: %s: .read() and .write() have stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))
0240
0241
0242 @ explain_rw_deadlocked depends on explain && reader_blocks @
0243 identifier fops_rw.openfunc;
0244 @@
0245 openfunc(...) {
0246 <...
0247 - nonseekable_open
0248 + nonseekable_open /* read & write (was deadlock) */
0249 ...>
0250 }
0251
0252
0253 @ explain_rw_nodeadlock depends on explain && !reader_blocks @
0254 identifier fops_rw.openfunc;
0255 @@
0256 openfunc(...) {
0257 <...
0258 - nonseekable_open
0259 + nonseekable_open /* read & write (no direct deadlock) */
0260 ...>
0261 }
0262
0263 @ patch_rw depends on patch @
0264 identifier fops_rw.openfunc;
0265 @@
0266 openfunc(...) {
0267 <...
0268 - nonseekable_open
0269 + stream_open
0270 ...>
0271 }
0272
0273
0274 // read, but not write
0275 @ fops_r depends on maybe_stream && !has_write @
0276 identifier fops0.fops, openfunc;
0277 identifier stream_reader.readstream;
0278 @@
0279 struct file_operations fops = {
0280 .open = openfunc,
0281 .read = readstream,
0282 };
0283
0284 @ report_r depends on report @
0285 identifier fops_r.openfunc;
0286 position p1;
0287 @@
0288 openfunc(...) {
0289 <...
0290 nonseekable_open@p1
0291 ...>
0292 }
0293
0294 @ script:python depends on report @
0295 fops << fops0.fops;
0296 p << report_r.p1;
0297 @@
0298 coccilib.report.print_report(p[0],
0299 "WARNING: %s: .read() has stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))
0300
0301 @ explain_r depends on explain @
0302 identifier fops_r.openfunc;
0303 @@
0304 openfunc(...) {
0305 <...
0306 - nonseekable_open
0307 + nonseekable_open /* read only */
0308 ...>
0309 }
0310
0311 @ patch_r depends on patch @
0312 identifier fops_r.openfunc;
0313 @@
0314 openfunc(...) {
0315 <...
0316 - nonseekable_open
0317 + stream_open
0318 ...>
0319 }
0320
0321
0322 // write, but not read
0323 @ fops_w depends on maybe_stream && !has_read @
0324 identifier fops0.fops, openfunc;
0325 identifier stream_writer.writestream;
0326 @@
0327 struct file_operations fops = {
0328 .open = openfunc,
0329 .write = writestream,
0330 };
0331
0332 @ report_w depends on report @
0333 identifier fops_w.openfunc;
0334 position p1;
0335 @@
0336 openfunc(...) {
0337 <...
0338 nonseekable_open@p1
0339 ...>
0340 }
0341
0342 @ script:python depends on report @
0343 fops << fops0.fops;
0344 p << report_w.p1;
0345 @@
0346 coccilib.report.print_report(p[0],
0347 "WARNING: %s: .write() has stream semantic; safe to change nonseekable_open -> stream_open." % (fops,))
0348
0349 @ explain_w depends on explain @
0350 identifier fops_w.openfunc;
0351 @@
0352 openfunc(...) {
0353 <...
0354 - nonseekable_open
0355 + nonseekable_open /* write only */
0356 ...>
0357 }
0358
0359 @ patch_w depends on patch @
0360 identifier fops_w.openfunc;
0361 @@
0362 openfunc(...) {
0363 <...
0364 - nonseekable_open
0365 + stream_open
0366 ...>
0367 }
0368
0369
0370 // no read, no write - don't change anything
