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-rw-r--r--fs/select.c106
-rw-r--r--include/linux/poll.h17
2 files changed, 81 insertions, 42 deletions
diff --git a/fs/select.c b/fs/select.c
index 1815a57d225..d8b4f0722b8 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -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;
@@ -64,13 +58,23 @@ 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;
@@ -78,8 +82,7 @@ void poll_freewait(struct poll_wqueues *pwq)
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;
@@ -89,12 +92,14 @@ 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;
@@ -102,7 +107,7 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
if (!new_table) {
p->error = -ENOMEM;
__set_current_state(TASK_RUNNING);
- return;
+ return NULL;
}
new_table->entry = new_table->entries;
new_table->next = table;
@@ -110,16 +115,21 @@ static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
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)
@@ -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
@@ -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)
@@ -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;
@@ -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;
}
@@ -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;
@@ -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();
@@ -645,14 +657,23 @@ 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
@@ -660,7 +681,7 @@ int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout)
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;
}
@@ -689,7 +710,8 @@ out_fds:
walk = head;
while(walk!=NULL) {
struct poll_list *pp = walk->next;
- kfree(walk);
+ if (walk != stack_pp)
+ kfree(walk);
walk = pp;
}
poll_freewait(&table);
diff --git a/include/linux/poll.h b/include/linux/poll.h
index 8e8f6098508..51e1b56741f 100644
--- a/include/linux/poll.h
+++ b/include/linux/poll.h
@@ -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;
/*
@@ -33,6 +42,12 @@ 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
*/
@@ -40,6 +55,8 @@ 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);
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-02 07:05:10 +0000