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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>
This commit is contained in:
Rusty Russell
parent
e969fed542
commit
2e04ef7691
17 changed files with 1906 additions and 1015 deletions
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@ -1,8 +1,10 @@
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/*P:200 This contains all the /dev/lguest code, whereby the userspace launcher
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/*P:200
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* This contains all the /dev/lguest code, whereby the userspace launcher
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* controls and communicates with the Guest. For example, the first write will
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* tell us the Guest's memory layout, pagetable, entry point and kernel address
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* offset. A read will run the Guest until something happens, such as a signal
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* or the Guest doing a NOTIFY out to the Launcher. :*/
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* or the Guest doing a NOTIFY out to the Launcher.
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:*/
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#include <linux/uaccess.h>
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#include <linux/miscdevice.h>
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#include <linux/fs.h>
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@ -37,8 +39,10 @@ static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
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if (!addr)
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return -EINVAL;
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/* Replace the old array with the new one, carefully: others can
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* be accessing it at the same time */
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/*
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* Replace the old array with the new one, carefully: others can
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* be accessing it at the same time.
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*/
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new = kmalloc(sizeof(*new) + sizeof(new->map[0]) * (old->num + 1),
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GFP_KERNEL);
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if (!new)
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@ -61,8 +65,10 @@ static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
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/* Now put new one in place. */
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rcu_assign_pointer(lg->eventfds, new);
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/* We're not in a big hurry. Wait until noone's looking at old
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* version, then delete it. */
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/*
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* We're not in a big hurry. Wait until noone's looking at old
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* version, then delete it.
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*/
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synchronize_rcu();
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kfree(old);
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@ -87,8 +93,10 @@ static int attach_eventfd(struct lguest *lg, const unsigned long __user *input)
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return err;
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}
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/*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
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* number to /dev/lguest. */
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/*L:050
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* Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
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* number to /dev/lguest.
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*/
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static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
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{
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unsigned long irq;
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@ -102,8 +110,10 @@ static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
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return 0;
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}
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/*L:040 Once our Guest is initialized, the Launcher makes it run by reading
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* from /dev/lguest. */
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/*L:040
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* Once our Guest is initialized, the Launcher makes it run by reading
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* from /dev/lguest.
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*/
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static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
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{
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struct lguest *lg = file->private_data;
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@ -139,8 +149,10 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
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return len;
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}
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/* If we returned from read() last time because the Guest sent I/O,
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* clear the flag. */
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/*
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* If we returned from read() last time because the Guest sent I/O,
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* clear the flag.
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*/
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if (cpu->pending_notify)
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cpu->pending_notify = 0;
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@ -148,8 +160,10 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
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return run_guest(cpu, (unsigned long __user *)user);
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}
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/*L:025 This actually initializes a CPU. For the moment, a Guest is only
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* uniprocessor, so "id" is always 0. */
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/*L:025
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* This actually initializes a CPU. For the moment, a Guest is only
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* uniprocessor, so "id" is always 0.
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*/
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static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
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{
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/* We have a limited number the number of CPUs in the lguest struct. */
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@ -164,8 +178,10 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
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/* Each CPU has a timer it can set. */
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init_clockdev(cpu);
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/* We need a complete page for the Guest registers: they are accessible
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* to the Guest and we can only grant it access to whole pages. */
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/*
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* We need a complete page for the Guest registers: they are accessible
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* to the Guest and we can only grant it access to whole pages.
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*/
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cpu->regs_page = get_zeroed_page(GFP_KERNEL);
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if (!cpu->regs_page)
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return -ENOMEM;
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@ -173,29 +189,38 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
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/* We actually put the registers at the bottom of the page. */
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cpu->regs = (void *)cpu->regs_page + PAGE_SIZE - sizeof(*cpu->regs);
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/* Now we initialize the Guest's registers, handing it the start
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* address. */
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/*
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* Now we initialize the Guest's registers, handing it the start
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* address.
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*/
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lguest_arch_setup_regs(cpu, start_ip);
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/* We keep a pointer to the Launcher task (ie. current task) for when
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* other Guests want to wake this one (eg. console input). */
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/*
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* We keep a pointer to the Launcher task (ie. current task) for when
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* other Guests want to wake this one (eg. console input).
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*/
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cpu->tsk = current;
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/* We need to keep a pointer to the Launcher's memory map, because if
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/*
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* We need to keep a pointer to the Launcher's memory map, because if
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* the Launcher dies we need to clean it up. If we don't keep a
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* reference, it is destroyed before close() is called. */
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* reference, it is destroyed before close() is called.
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*/
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cpu->mm = get_task_mm(cpu->tsk);
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/* We remember which CPU's pages this Guest used last, for optimization
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* when the same Guest runs on the same CPU twice. */
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/*
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* We remember which CPU's pages this Guest used last, for optimization
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* when the same Guest runs on the same CPU twice.
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*/
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cpu->last_pages = NULL;
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/* No error == success. */
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return 0;
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}
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/*L:020 The initialization write supplies 3 pointer sized (32 or 64 bit)
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* values (in addition to the LHREQ_INITIALIZE value). These are:
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/*L:020
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* The initialization write supplies 3 pointer sized (32 or 64 bit) values (in
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* addition to the LHREQ_INITIALIZE value). These are:
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*
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* base: The start of the Guest-physical memory inside the Launcher memory.
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*
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@ -207,14 +232,15 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
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*/
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static int initialize(struct file *file, const unsigned long __user *input)
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{
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/* "struct lguest" contains everything we (the Host) know about a
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* Guest. */
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/* "struct lguest" contains all we (the Host) know about a Guest. */
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struct lguest *lg;
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int err;
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unsigned long args[3];
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/* We grab the Big Lguest lock, which protects against multiple
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* simultaneous initializations. */
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/*
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* We grab the Big Lguest lock, which protects against multiple
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* simultaneous initializations.
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*/
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mutex_lock(&lguest_lock);
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/* You can't initialize twice! Close the device and start again... */
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if (file->private_data) {
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@ -249,8 +275,10 @@ static int initialize(struct file *file, const unsigned long __user *input)
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if (err)
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goto free_eventfds;
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/* Initialize the Guest's shadow page tables, using the toplevel
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* address the Launcher gave us. This allocates memory, so can fail. */
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/*
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* Initialize the Guest's shadow page tables, using the toplevel
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* address the Launcher gave us. This allocates memory, so can fail.
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*/
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err = init_guest_pagetable(lg);
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if (err)
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goto free_regs;
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@ -275,7 +303,8 @@ unlock:
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return err;
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}
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/*L:010 The first operation the Launcher does must be a write. All writes
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/*L:010
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* The first operation the Launcher does must be a write. All writes
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* start with an unsigned long number: for the first write this must be
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* LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use
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* writes of other values to send interrupts.
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@ -283,12 +312,15 @@ unlock:
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* Note that we overload the "offset" in the /dev/lguest file to indicate what
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* CPU number we're dealing with. Currently this is always 0, since we only
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* support uniprocessor Guests, but you can see the beginnings of SMP support
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* here. */
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* here.
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*/
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static ssize_t write(struct file *file, const char __user *in,
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size_t size, loff_t *off)
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{
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/* Once the Guest is initialized, we hold the "struct lguest" in the
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* file private data. */
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/*
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* Once the Guest is initialized, we hold the "struct lguest" in the
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* file private data.
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*/
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struct lguest *lg = file->private_data;
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const unsigned long __user *input = (const unsigned long __user *)in;
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unsigned long req;
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@ -323,13 +355,15 @@ static ssize_t write(struct file *file, const char __user *in,
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}
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}
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/*L:060 The final piece of interface code is the close() routine. It reverses
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/*L:060
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* The final piece of interface code is the close() routine. It reverses
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* everything done in initialize(). This is usually called because the
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* Launcher exited.
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*
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* Note that the close routine returns 0 or a negative error number: it can't
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* really fail, but it can whine. I blame Sun for this wart, and K&R C for
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* letting them do it. :*/
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* letting them do it.
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:*/
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static int close(struct inode *inode, struct file *file)
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{
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struct lguest *lg = file->private_data;
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@ -339,8 +373,10 @@ static int close(struct inode *inode, struct file *file)
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if (!lg)
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return 0;
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/* We need the big lock, to protect from inter-guest I/O and other
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* Launchers initializing guests. */
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/*
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* We need the big lock, to protect from inter-guest I/O and other
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* Launchers initializing guests.
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*/
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mutex_lock(&lguest_lock);
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/* Free up the shadow page tables for the Guest. */
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@ -351,8 +387,10 @@ static int close(struct inode *inode, struct file *file)
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hrtimer_cancel(&lg->cpus[i].hrt);
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/* We can free up the register page we allocated. */
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free_page(lg->cpus[i].regs_page);
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/* Now all the memory cleanups are done, it's safe to release
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* the Launcher's memory management structure. */
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/*
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* Now all the memory cleanups are done, it's safe to release
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* the Launcher's memory management structure.
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*/
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mmput(lg->cpus[i].mm);
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}
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@ -361,8 +399,10 @@ static int close(struct inode *inode, struct file *file)
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eventfd_ctx_put(lg->eventfds->map[i].event);
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kfree(lg->eventfds);
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/* If lg->dead doesn't contain an error code it will be NULL or a
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* kmalloc()ed string, either of which is ok to hand to kfree(). */
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/*
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* If lg->dead doesn't contain an error code it will be NULL or a
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* kmalloc()ed string, either of which is ok to hand to kfree().
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*/
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if (!IS_ERR(lg->dead))
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kfree(lg->dead);
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/* Free the memory allocated to the lguest_struct */
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@ -386,7 +426,8 @@ static int close(struct inode *inode, struct file *file)
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*
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* We begin our understanding with the Host kernel interface which the Launcher
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* uses: reading and writing a character device called /dev/lguest. All the
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* work happens in the read(), write() and close() routines: */
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* work happens in the read(), write() and close() routines:
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*/
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static struct file_operations lguest_fops = {
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.owner = THIS_MODULE,
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.release = close,
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@ -394,8 +435,10 @@ static struct file_operations lguest_fops = {
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.read = read,
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};
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/* This is a textbook example of a "misc" character device. Populate a "struct
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* miscdevice" and register it with misc_register(). */
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/*
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* This is a textbook example of a "misc" character device. Populate a "struct
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* miscdevice" and register it with misc_register().
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*/
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static struct miscdevice lguest_dev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "lguest",
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