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yaml
---
r: 24476
b: refs/heads/master
c: 70674f9
h: refs/heads/master
v: v3
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Andi Kleen authored and Linus Torvalds committed Mar 28, 2006
1 parent c541128 commit 080516f
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Showing 3 changed files with 82 additions and 43 deletions.
2 changes: 1 addition & 1 deletion [refs]
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Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: b02389e98a7b64ad5cd4823740defa8821f30bbd
refs/heads/master: 70674f95c0a2ea694d5c39f4e514f538a09be36f
106 changes: 64 additions & 42 deletions trunk/fs/select.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,12 +29,6 @@
#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)

struct poll_table_entry {
struct file * filp;
wait_queue_t wait;
wait_queue_head_t * wait_address;
};

struct poll_table_page {
struct poll_table_page * next;
struct poll_table_entry * entry;
Expand Down Expand Up @@ -64,22 +58,31 @@ void poll_initwait(struct poll_wqueues *pwq)
init_poll_funcptr(&pwq->pt, __pollwait);
pwq->error = 0;
pwq->table = NULL;
pwq->inline_index = 0;
}

EXPORT_SYMBOL(poll_initwait);

static void free_poll_entry(struct poll_table_entry *entry)
{
remove_wait_queue(entry->wait_address,&entry->wait);
fput(entry->filp);
}

void poll_freewait(struct poll_wqueues *pwq)
{
struct poll_table_page * p = pwq->table;
int i;
for (i = 0; i < pwq->inline_index; i++)
free_poll_entry(pwq->inline_entries + i);
while (p) {
struct poll_table_entry * entry;
struct poll_table_page *old;

entry = p->entry;
do {
entry--;
remove_wait_queue(entry->wait_address,&entry->wait);
fput(entry->filp);
free_poll_entry(entry);
} while (entry > p->entries);
old = p;
p = p->next;
Expand All @@ -89,37 +92,44 @@ void poll_freewait(struct poll_wqueues *pwq)

EXPORT_SYMBOL(poll_freewait);

static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
poll_table *_p)
static struct poll_table_entry *poll_get_entry(poll_table *_p)
{
struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
struct poll_table_page *table = p->table;

if (p->inline_index < N_INLINE_POLL_ENTRIES)
return p->inline_entries + p->inline_index++;

if (!table || POLL_TABLE_FULL(table)) {
struct poll_table_page *new_table;

new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
if (!new_table) {
p->error = -ENOMEM;
__set_current_state(TASK_RUNNING);
return;
return NULL;
}
new_table->entry = new_table->entries;
new_table->next = table;
p->table = new_table;
table = new_table;
}

/* Add a new entry */
{
struct poll_table_entry * entry = table->entry;
table->entry = entry+1;
get_file(filp);
entry->filp = filp;
entry->wait_address = wait_address;
init_waitqueue_entry(&entry->wait, current);
add_wait_queue(wait_address,&entry->wait);
}
return table->entry++;
}

/* Add a new entry */
static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
poll_table *p)
{
struct poll_table_entry *entry = poll_get_entry(p);
if (!entry)
return;
get_file(filp);
entry->filp = filp;
entry->wait_address = wait_address;
init_waitqueue_entry(&entry->wait, current);
add_wait_queue(wait_address,&entry->wait);
}

#define FDS_IN(fds, n) (fds->in + n)
Expand Down Expand Up @@ -284,16 +294,6 @@ int do_select(int n, fd_set_bits *fds, s64 *timeout)
return retval;
}

static void *select_bits_alloc(int size)
{
return kmalloc(6 * size, GFP_KERNEL);
}

static void select_bits_free(void *bits, int size)
{
kfree(bits);
}

/*
* We can actually return ERESTARTSYS instead of EINTR, but I'd
* like to be certain this leads to no problems. So I return
Expand All @@ -312,6 +312,8 @@ static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
char *bits;
int ret, size, max_fdset;
struct fdtable *fdt;
/* Allocate small arguments on the stack to save memory and be faster */
char stack_fds[SELECT_STACK_ALLOC];

ret = -EINVAL;
if (n < 0)
Expand All @@ -332,7 +334,10 @@ static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
*/
ret = -ENOMEM;
size = FDS_BYTES(n);
bits = select_bits_alloc(size);
if (6*size < SELECT_STACK_ALLOC)
bits = stack_fds;
else
bits = kmalloc(6 * size, GFP_KERNEL);
if (!bits)
goto out_nofds;
fds.in = (unsigned long *) bits;
Expand Down Expand Up @@ -367,7 +372,8 @@ static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
ret = -EFAULT;

out:
select_bits_free(bits, size);
if (bits != stack_fds)
kfree(bits);
out_nofds:
return ret;
}
Expand Down Expand Up @@ -619,6 +625,9 @@ static int do_poll(unsigned int nfds, struct poll_list *list,
return count;
}

#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
sizeof(struct pollfd))

int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
{
struct poll_wqueues table;
Expand All @@ -628,6 +637,9 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
struct poll_list *walk;
struct fdtable *fdt;
int max_fdset;
/* Allocate small arguments on the stack to save memory and be faster */
char stack_pps[POLL_STACK_ALLOC];
struct poll_list *stack_pp = NULL;

/* Do a sanity check on nfds ... */
rcu_read_lock();
Expand All @@ -645,22 +657,31 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
err = -ENOMEM;
while(i!=0) {
struct poll_list *pp;
pp = kmalloc(sizeof(struct poll_list)+
sizeof(struct pollfd)*
(i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i),
GFP_KERNEL);
if(pp==NULL)
goto out_fds;
int num, size;
if (stack_pp == NULL)
num = N_STACK_PPS;
else
num = POLLFD_PER_PAGE;
if (num > i)
num = i;
size = sizeof(struct poll_list) + sizeof(struct pollfd)*num;
if (!stack_pp)
stack_pp = pp = (struct poll_list *)stack_pps;
else {
pp = kmalloc(size, GFP_KERNEL);
if (!pp)
goto out_fds;
}
pp->next=NULL;
pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
pp->len = num;
if (head == NULL)
head = pp;
else
walk->next = pp;

walk = pp;
if (copy_from_user(pp->entries, ufds + nfds-i,
sizeof(struct pollfd)*pp->len)) {
sizeof(struct pollfd)*num)) {
err = -EFAULT;
goto out_fds;
}
Expand Down Expand Up @@ -689,7 +710,8 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
walk = head;
while(walk!=NULL) {
struct poll_list *pp = walk->next;
kfree(walk);
if (walk != stack_pp)
kfree(walk);
walk = pp;
}
poll_freewait(&table);
Expand Down
17 changes: 17 additions & 0 deletions trunk/include/linux/poll.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,15 @@
#include <linux/mm.h>
#include <asm/uaccess.h>

/* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
additional memory. */
#define MAX_STACK_ALLOC 832
#define FRONTEND_STACK_ALLOC 256
#define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC
#define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC
#define WQUEUES_STACK_ALLOC (MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
#define N_INLINE_POLL_ENTRIES (WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))

struct poll_table_struct;

/*
Expand All @@ -33,13 +42,21 @@ static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
pt->qproc = qproc;
}

struct poll_table_entry {
struct file * filp;
wait_queue_t wait;
wait_queue_head_t * wait_address;
};

/*
* Structures and helpers for sys_poll/sys_poll
*/
struct poll_wqueues {
poll_table pt;
struct poll_table_page * table;
int error;
int inline_index;
struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];
};

extern void poll_initwait(struct poll_wqueues *pwq);
Expand Down

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