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authorRusty Russell <rusty@rustcorp.com.au>2009-07-30 18:03:45 -0400
committerRusty Russell <rusty@rustcorp.com.au>2009-07-30 02:33:45 -0400
commit2e04ef76916d1e29a077ea9d0f2003c8fd86724d (patch)
tree2ff8d625d6e467be9f9f1b67a3674cb6e125e970 /drivers/lguest/lguest_user.c
parente969fed542cae08cb11d666efac4f7c5d624d09f (diff)
lguest: fix comment style
I don't really notice it (except to begrudge the extra vertical space), but Ingo does. And he pointed out that one excuse of lguest is as a teaching tool, it should set a good example. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>
Diffstat (limited to 'drivers/lguest/lguest_user.c')
-rw-r--r--drivers/lguest/lguest_user.c137
1 files changed, 90 insertions, 47 deletions
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 407722a8e0c4..7e92017103dc 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -1,8 +1,10 @@
1/*P:200 This contains all the /dev/lguest code, whereby the userspace launcher 1/*P:200
2 * This contains all the /dev/lguest code, whereby the userspace launcher
2 * controls and communicates with the Guest. For example, the first write will 3 * controls and communicates with the Guest. For example, the first write will
3 * tell us the Guest's memory layout, pagetable, entry point and kernel address 4 * tell us the Guest's memory layout, pagetable, entry point and kernel address
4 * offset. A read will run the Guest until something happens, such as a signal 5 * offset. A read will run the Guest until something happens, such as a signal
5 * or the Guest doing a NOTIFY out to the Launcher. :*/ 6 * or the Guest doing a NOTIFY out to the Launcher.
7:*/
6#include <linux/uaccess.h> 8#include <linux/uaccess.h>
7#include <linux/miscdevice.h> 9#include <linux/miscdevice.h>
8#include <linux/fs.h> 10#include <linux/fs.h>
@@ -37,8 +39,10 @@ static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
37 if (!addr) 39 if (!addr)
38 return -EINVAL; 40 return -EINVAL;
39 41
40 /* Replace the old array with the new one, carefully: others can 42 /*
41 * be accessing it at the same time */ 43 * Replace the old array with the new one, carefully: others can
44 * be accessing it at the same time.
45 */
42 new = kmalloc(sizeof(*new) + sizeof(new->map[0]) * (old->num + 1), 46 new = kmalloc(sizeof(*new) + sizeof(new->map[0]) * (old->num + 1),
43 GFP_KERNEL); 47 GFP_KERNEL);
44 if (!new) 48 if (!new)
@@ -61,8 +65,10 @@ static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
61 /* Now put new one in place. */ 65 /* Now put new one in place. */
62 rcu_assign_pointer(lg->eventfds, new); 66 rcu_assign_pointer(lg->eventfds, new);
63 67
64 /* We're not in a big hurry. Wait until noone's looking at old 68 /*
65 * version, then delete it. */ 69 * We're not in a big hurry. Wait until noone's looking at old
70 * version, then delete it.
71 */
66 synchronize_rcu(); 72 synchronize_rcu();
67 kfree(old); 73 kfree(old);
68 74
@@ -87,8 +93,10 @@ static int attach_eventfd(struct lguest *lg, const unsigned long __user *input)
87 return err; 93 return err;
88} 94}
89 95
90/*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt 96/*L:050
91 * number to /dev/lguest. */ 97 * Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
98 * number to /dev/lguest.
99 */
92static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input) 100static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
93{ 101{
94 unsigned long irq; 102 unsigned long irq;
@@ -102,8 +110,10 @@ static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
102 return 0; 110 return 0;
103} 111}
104 112
105/*L:040 Once our Guest is initialized, the Launcher makes it run by reading 113/*L:040
106 * from /dev/lguest. */ 114 * Once our Guest is initialized, the Launcher makes it run by reading
115 * from /dev/lguest.
116 */
107static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o) 117static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
108{ 118{
109 struct lguest *lg = file->private_data; 119 struct lguest *lg = file->private_data;
@@ -139,8 +149,10 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
139 return len; 149 return len;
140 } 150 }
141 151
142 /* If we returned from read() last time because the Guest sent I/O, 152 /*
143 * clear the flag. */ 153 * If we returned from read() last time because the Guest sent I/O,
154 * clear the flag.
155 */
144 if (cpu->pending_notify) 156 if (cpu->pending_notify)
145 cpu->pending_notify = 0; 157 cpu->pending_notify = 0;
146 158
@@ -148,8 +160,10 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
148 return run_guest(cpu, (unsigned long __user *)user); 160 return run_guest(cpu, (unsigned long __user *)user);
149} 161}
150 162
151/*L:025 This actually initializes a CPU. For the moment, a Guest is only 163/*L:025
152 * uniprocessor, so "id" is always 0. */ 164 * This actually initializes a CPU. For the moment, a Guest is only
165 * uniprocessor, so "id" is always 0.
166 */
153static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip) 167static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
154{ 168{
155 /* We have a limited number the number of CPUs in the lguest struct. */ 169 /* We have a limited number the number of CPUs in the lguest struct. */
@@ -164,8 +178,10 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
164 /* Each CPU has a timer it can set. */ 178 /* Each CPU has a timer it can set. */
165 init_clockdev(cpu); 179 init_clockdev(cpu);
166 180
167 /* We need a complete page for the Guest registers: they are accessible 181 /*
168 * to the Guest and we can only grant it access to whole pages. */ 182 * We need a complete page for the Guest registers: they are accessible
183 * to the Guest and we can only grant it access to whole pages.
184 */
169 cpu->regs_page = get_zeroed_page(GFP_KERNEL); 185 cpu->regs_page = get_zeroed_page(GFP_KERNEL);
170 if (!cpu->regs_page) 186 if (!cpu->regs_page)
171 return -ENOMEM; 187 return -ENOMEM;
@@ -173,29 +189,38 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
173 /* We actually put the registers at the bottom of the page. */ 189 /* We actually put the registers at the bottom of the page. */
174 cpu->regs = (void *)cpu->regs_page + PAGE_SIZE - sizeof(*cpu->regs); 190 cpu->regs = (void *)cpu->regs_page + PAGE_SIZE - sizeof(*cpu->regs);
175 191
176 /* Now we initialize the Guest's registers, handing it the start 192 /*
177 * address. */ 193 * Now we initialize the Guest's registers, handing it the start
194 * address.
195 */
178 lguest_arch_setup_regs(cpu, start_ip); 196 lguest_arch_setup_regs(cpu, start_ip);
179 197
180 /* We keep a pointer to the Launcher task (ie. current task) for when 198 /*
181 * other Guests want to wake this one (eg. console input). */ 199 * We keep a pointer to the Launcher task (ie. current task) for when
200 * other Guests want to wake this one (eg. console input).
201 */
182 cpu->tsk = current; 202 cpu->tsk = current;
183 203
184 /* We need to keep a pointer to the Launcher's memory map, because if 204 /*
205 * We need to keep a pointer to the Launcher's memory map, because if
185 * the Launcher dies we need to clean it up. If we don't keep a 206 * the Launcher dies we need to clean it up. If we don't keep a
186 * reference, it is destroyed before close() is called. */ 207 * reference, it is destroyed before close() is called.
208 */
187 cpu->mm = get_task_mm(cpu->tsk); 209 cpu->mm = get_task_mm(cpu->tsk);
188 210
189 /* We remember which CPU's pages this Guest used last, for optimization 211 /*
190 * when the same Guest runs on the same CPU twice. */ 212 * We remember which CPU's pages this Guest used last, for optimization
213 * when the same Guest runs on the same CPU twice.
214 */
191 cpu->last_pages = NULL; 215 cpu->last_pages = NULL;
192 216
193 /* No error == success. */ 217 /* No error == success. */
194 return 0; 218 return 0;
195} 219}
196 220
197/*L:020 The initialization write supplies 3 pointer sized (32 or 64 bit) 221/*L:020
198 * values (in addition to the LHREQ_INITIALIZE value). These are: 222 * The initialization write supplies 3 pointer sized (32 or 64 bit) values (in
223 * addition to the LHREQ_INITIALIZE value). These are:
199 * 224 *
200 * base: The start of the Guest-physical memory inside the Launcher memory. 225 * base: The start of the Guest-physical memory inside the Launcher memory.
201 * 226 *
@@ -207,14 +232,15 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
207 */ 232 */
208static int initialize(struct file *file, const unsigned long __user *input) 233static int initialize(struct file *file, const unsigned long __user *input)
209{ 234{
210 /* "struct lguest" contains everything we (the Host) know about a 235 /* "struct lguest" contains all we (the Host) know about a Guest. */
211 * Guest. */
212 struct lguest *lg; 236 struct lguest *lg;
213 int err; 237 int err;
214 unsigned long args[3]; 238 unsigned long args[3];
215 239
216 /* We grab the Big Lguest lock, which protects against multiple 240 /*
217 * simultaneous initializations. */ 241 * We grab the Big Lguest lock, which protects against multiple
242 * simultaneous initializations.
243 */
218 mutex_lock(&lguest_lock); 244 mutex_lock(&lguest_lock);
219 /* You can't initialize twice! Close the device and start again... */ 245 /* You can't initialize twice! Close the device and start again... */
220 if (file->private_data) { 246 if (file->private_data) {
@@ -249,8 +275,10 @@ static int initialize(struct file *file, const unsigned long __user *input)
249 if (err) 275 if (err)
250 goto free_eventfds; 276 goto free_eventfds;
251 277
252 /* Initialize the Guest's shadow page tables, using the toplevel 278 /*
253 * address the Launcher gave us. This allocates memory, so can fail. */ 279 * Initialize the Guest's shadow page tables, using the toplevel
280 * address the Launcher gave us. This allocates memory, so can fail.
281 */
254 err = init_guest_pagetable(lg); 282 err = init_guest_pagetable(lg);
255 if (err) 283 if (err)
256 goto free_regs; 284 goto free_regs;
@@ -275,7 +303,8 @@ unlock:
275 return err; 303 return err;
276} 304}
277 305
278/*L:010 The first operation the Launcher does must be a write. All writes 306/*L:010
307 * The first operation the Launcher does must be a write. All writes
279 * start with an unsigned long number: for the first write this must be 308 * start with an unsigned long number: for the first write this must be
280 * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use 309 * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use
281 * writes of other values to send interrupts. 310 * writes of other values to send interrupts.
@@ -283,12 +312,15 @@ unlock:
283 * Note that we overload the "offset" in the /dev/lguest file to indicate what 312 * Note that we overload the "offset" in the /dev/lguest file to indicate what
284 * CPU number we're dealing with. Currently this is always 0, since we only 313 * CPU number we're dealing with. Currently this is always 0, since we only
285 * support uniprocessor Guests, but you can see the beginnings of SMP support 314 * support uniprocessor Guests, but you can see the beginnings of SMP support
286 * here. */ 315 * here.
316 */
287static ssize_t write(struct file *file, const char __user *in, 317static ssize_t write(struct file *file, const char __user *in,
288 size_t size, loff_t *off) 318 size_t size, loff_t *off)
289{ 319{
290 /* Once the Guest is initialized, we hold the "struct lguest" in the 320 /*
291 * file private data. */ 321 * Once the Guest is initialized, we hold the "struct lguest" in the
322 * file private data.
323 */
292 struct lguest *lg = file->private_data; 324 struct lguest *lg = file->private_data;
293 const unsigned long __user *input = (const unsigned long __user *)in; 325 const unsigned long __user *input = (const unsigned long __user *)in;
294 unsigned long req; 326 unsigned long req;
@@ -323,13 +355,15 @@ static ssize_t write(struct file *file, const char __user *in,
323 } 355 }
324} 356}
325 357
326/*L:060 The final piece of interface code is the close() routine. It reverses 358/*L:060
359 * The final piece of interface code is the close() routine. It reverses
327 * everything done in initialize(). This is usually called because the 360 * everything done in initialize(). This is usually called because the
328 * Launcher exited. 361 * Launcher exited.
329 * 362 *
330 * Note that the close routine returns 0 or a negative error number: it can't 363 * Note that the close routine returns 0 or a negative error number: it can't
331 * really fail, but it can whine. I blame Sun for this wart, and K&R C for 364 * really fail, but it can whine. I blame Sun for this wart, and K&R C for
332 * letting them do it. :*/ 365 * letting them do it.
366:*/
333static int close(struct inode *inode, struct file *file) 367static int close(struct inode *inode, struct file *file)
334{ 368{
335 struct lguest *lg = file->private_data; 369 struct lguest *lg = file->private_data;
@@ -339,8 +373,10 @@ static int close(struct inode *inode, struct file *file)
339 if (!lg) 373 if (!lg)
340 return 0; 374 return 0;
341 375
342 /* We need the big lock, to protect from inter-guest I/O and other 376 /*
343 * Launchers initializing guests. */ 377 * We need the big lock, to protect from inter-guest I/O and other
378 * Launchers initializing guests.
379 */
344 mutex_lock(&lguest_lock); 380 mutex_lock(&lguest_lock);
345 381
346 /* Free up the shadow page tables for the Guest. */ 382 /* Free up the shadow page tables for the Guest. */
@@ -351,8 +387,10 @@ static int close(struct inode *inode, struct file *file)
351 hrtimer_cancel(&lg->cpus[i].hrt); 387 hrtimer_cancel(&lg->cpus[i].hrt);
352 /* We can free up the register page we allocated. */ 388 /* We can free up the register page we allocated. */
353 free_page(lg->cpus[i].regs_page); 389 free_page(lg->cpus[i].regs_page);
354 /* Now all the memory cleanups are done, it's safe to release 390 /*
355 * the Launcher's memory management structure. */ 391 * Now all the memory cleanups are done, it's safe to release
392 * the Launcher's memory management structure.
393 */
356 mmput(lg->cpus[i].mm); 394 mmput(lg->cpus[i].mm);
357 } 395 }
358 396
@@ -361,8 +399,10 @@ static int close(struct inode *inode, struct file *file)
361 eventfd_ctx_put(lg->eventfds->map[i].event); 399 eventfd_ctx_put(lg->eventfds->map[i].event);
362 kfree(lg->eventfds); 400 kfree(lg->eventfds);
363 401
364 /* If lg->dead doesn't contain an error code it will be NULL or a 402 /*
365 * kmalloc()ed string, either of which is ok to hand to kfree(). */ 403 * If lg->dead doesn't contain an error code it will be NULL or a
404 * kmalloc()ed string, either of which is ok to hand to kfree().
405 */
366 if (!IS_ERR(lg->dead)) 406 if (!IS_ERR(lg->dead))
367 kfree(lg->dead); 407 kfree(lg->dead);
368 /* Free the memory allocated to the lguest_struct */ 408 /* Free the memory allocated to the lguest_struct */
@@ -386,7 +426,8 @@ static int close(struct inode *inode, struct file *file)
386 * 426 *
387 * We begin our understanding with the Host kernel interface which the Launcher 427 * We begin our understanding with the Host kernel interface which the Launcher
388 * uses: reading and writing a character device called /dev/lguest. All the 428 * uses: reading and writing a character device called /dev/lguest. All the
389 * work happens in the read(), write() and close() routines: */ 429 * work happens in the read(), write() and close() routines:
430 */
390static struct file_operations lguest_fops = { 431static struct file_operations lguest_fops = {
391 .owner = THIS_MODULE, 432 .owner = THIS_MODULE,
392 .release = close, 433 .release = close,
@@ -394,8 +435,10 @@ static struct file_operations lguest_fops = {
394 .read = read, 435 .read = read,
395}; 436};
396 437
397/* This is a textbook example of a "misc" character device. Populate a "struct 438/*
398 * miscdevice" and register it with misc_register(). */ 439 * This is a textbook example of a "misc" character device. Populate a "struct
440 * miscdevice" and register it with misc_register().
441 */
399static struct miscdevice lguest_dev = { 442static struct miscdevice lguest_dev = {
400 .minor = MISC_DYNAMIC_MINOR, 443 .minor = MISC_DYNAMIC_MINOR,
401 .name = "lguest", 444 .name = "lguest",