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feat: proper cleanup for shared pages

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This commit is contained in:
Gleb Koval
2024-12-04 12:27:39 +00:00
parent f2aba977b4
commit c0ff53beff
3 changed files with 85 additions and 18 deletions
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6
src/userprog/process.c
View File

@@ -172,8 +172,9 @@ start_process (void *proc_start_data)
to store the command that executed the process. */
if (data->success)
{
data->success =
process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
data->success = use_shared_file (exec_file)
&& process_init_stack (data->cmd_saveptr, &if_.esp,
data->file_name);
}
/* Signal that the process has finished attempting to load. */
@@ -366,6 +367,7 @@ process_exit (void)
/* Clean up all open files */
hash_destroy (&cur->open_files, fd_cleanup);
hash_destroy (&cur->pages, page_cleanup);
unuse_shared_file (cur->exec_file);
/* Close the executable file, implicitly allowing it to be written to. */
if (cur->exec_file != NULL)

95
src/vm/page.c
View File

@@ -12,14 +12,19 @@
static unsigned page_hash (const struct hash_elem *e, void *aux UNUSED);
static bool page_less (const struct hash_elem *a_, const struct hash_elem *b_,
void *aux UNUSED);
static struct shared_file_entry *shared_file_insert (struct file *file);
static struct shared_page_entry *shared_page_insert (struct file *file,
void *upage, void *frame);
static struct shared_file_entry *shared_file_get (struct file *file);
static struct shared_page_entry *shared_page_get (struct file *file,
void *upage);
static unsigned shared_file_hash (const struct hash_elem *e, void *aux UNUSED);
static bool shared_file_less (const struct hash_elem *a_,
const struct hash_elem *b_, void *aux UNUSED);
static unsigned shared_page_hash (const struct hash_elem *e, void *aux UNUSED);
static bool shared_page_less (const struct hash_elem *a_,
const struct hash_elem *b_, void *aux UNUSED);
static void shared_page_cleanup (struct hash_elem *e, void *aux UNUSED);
/* Initialise a thread's supplemental pages table. */
bool
@@ -180,7 +185,7 @@ page_cleanup (struct hash_elem *e, void *aux UNUSED)
}
/* Initialise the shared files and table and lock. */
bool
void
shared_files_init ()
{
lock_init (&shared_files_lock);
@@ -188,16 +193,64 @@ shared_files_init ()
PANIC ("Failed to initialise shared_files table.");
}
bool
use_shared_file (struct file *file)
{
lock_acquire (&shared_files_lock);
struct shared_file_entry *shared_file = shared_file_get (file);
if (shared_file == NULL)
{
shared_file = shared_file_insert (file);
if (shared_file == NULL)
{
lock_release (&shared_files_lock);
return false;
}
}
shared_file->ref_count++;
lock_release (&shared_files_lock);
return true;
}
bool
unuse_shared_file (struct file *file)
{
lock_acquire (&shared_files_lock);
struct shared_file_entry *shared_file = shared_file_get (file);
if (shared_file == NULL)
{
lock_release (&shared_files_lock);
return false;
}
shared_file->ref_count--;
if (shared_file->ref_count <= 0)
{
hash_destroy (&shared_file->pages, shared_page_cleanup);
hash_delete (&shared_files, &shared_file->elem);
free (shared_file);
}
lock_release (&shared_files_lock);
}
static void
shared_page_cleanup (struct hash_elem *e, void *aux UNUSED)
{
struct shared_page_entry *shared_page
= hash_entry (e, struct shared_page_entry, elem);
// frame_free (shared_page->frame);
free (shared_page);
}
/* Hashing function needed for the shared_file table. Returns a hash for an
entry based on its file pointer. */
unsigned
static unsigned
shared_file_hash (const struct hash_elem *e, void *aux UNUSED)
{
return file_hash (hash_entry (e, struct shared_file_entry, elem)->file);
}
/* Less function needed for the shared_file table. */
bool
static bool
shared_file_less (const struct hash_elem *a_, const struct hash_elem *b_,
void *aux UNUSED)
{
@@ -246,7 +299,7 @@ shared_file_get (struct file *file)
/* Gets a shared_page_entry from the shared_pages table using the file and upage
of the page. Returns NULL if no such page_entry exists in the hash map.*/
struct shared_page_entry *
static struct shared_page_entry *
shared_page_get (struct file *file, void *upage)
{
/* Search first for the file within the shared_pages structure */
@@ -266,6 +319,27 @@ shared_page_get (struct file *file, void *upage)
return hash_entry (e, struct shared_page_entry, elem);
}
static struct shared_file_entry *
shared_file_insert (struct file *file)
{
struct shared_file_entry *shared_file
= malloc (sizeof (struct shared_file_entry));
if (shared_file == NULL)
return NULL;
shared_file->file = file;
shared_file->ref_count = 0;
if (!hash_init (&shared_file->pages, shared_page_hash, shared_page_less,
NULL))
{
free (shared_file);
return NULL;
}
hash_insert (&shared_files, &shared_file->elem);
return shared_file;
}
static struct shared_page_entry *
shared_page_insert (struct file *file, void *upage, void *frame)
{
@@ -280,23 +354,12 @@ shared_page_insert (struct file *file, void *upage, void *frame)
/* If shared file doesn't exist in table, also create it. */
if (shared_file == NULL)
{
shared_file = malloc (sizeof (struct shared_file_entry));
shared_file = shared_file_insert (file);
if (shared_file == NULL)
{
free (shared_page);
return NULL;
}
shared_file->file = file;
shared_file->ref_count = 0;
if (!hash_init (&shared_file->pages, shared_page_hash, shared_page_less, NULL))
{
free (shared_page);
free (shared_file);
return NULL;
}
hash_insert (&shared_files, &shared_file->elem);
}
shared_page->upage = upage;

2
src/vm/page.h
View File

@@ -52,6 +52,8 @@ bool page_load (struct page_entry *page);
void page_cleanup (struct hash_elem *e, void *aux UNUSED);
void shared_files_init ();
bool use_shared_file (struct file *file);
bool unuse_shared_file (struct file *file);
void page_set_swap (struct thread *, void *, size_t);
size_t page_get_swap (struct thread *, void *);