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authorLinus Torvalds <torvalds@penguin.transmeta.com>2002-06-18 04:34:49 -0700
committerLinus Torvalds <torvalds@penguin.transmeta.com>2002-06-18 04:34:49 -0700
commit8733e61147e3e0fcd7a24792b5e5e3cc02ece354 (patch)
treecef5f6f5fb7bcdbc74a6d13b03fc81a03e54f588
parentab6094f9f6c5a3ea954d58aa6bb9090d6e71487f (diff)
revert broken select optimizations
Cset exclude: torvalds@penguin.transmeta.com|ChangeSet|20020619003306|07760 Cset exclude: ak@muc.de|ChangeSet|20020618172743|19150
-rw-r--r--fs/select.c317
-rw-r--r--include/linux/poll.h49
2 files changed, 180 insertions, 186 deletions
diff --git a/fs/select.c b/fs/select.c
index 9fd7fb136200..30c29f1e49f8 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -12,9 +12,6 @@
* 24 January 2000
* Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
* of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
- *
- * Dec 2001
- * Stack allocation and fast path (Andi Kleen)
*/
#include <linux/slab.h>
@@ -29,6 +26,21 @@
#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;
+ struct poll_table_entry entries[0];
+};
+
+#define POLL_TABLE_FULL(table) \
+ ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
+
/*
* Ok, Peter made a complicated, but straightforward multiple_wait() function.
* I have rewritten this, taking some shortcuts: This code may not be easy to
@@ -50,39 +62,30 @@ void poll_freewait(poll_table* pt)
struct poll_table_page *old;
entry = p->entry;
- while (entry > p->entries) {
+ do {
entry--;
remove_wait_queue(entry->wait_address,&entry->wait);
fput(entry->filp);
- }
+ } while (entry > p->entries);
old = p;
p = p->next;
- if (old != &pt->inline_page)
- free_page((unsigned long) old);
+ free_page((unsigned long) old);
}
}
void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
{
struct poll_table_page *table = p->table;
- struct poll_table_page *new_table = NULL;
- int sz;
-
- if (!table) {
- new_table = &p->inline_page;
- } else {
- sz = (table == &p->inline_page) ? POLL_INLINE_TABLE_LEN : PAGE_SIZE;
- if ((char*)table->entry >= (char*)table + sz) {
- new_table = (struct poll_table_page *)__get_free_page(GFP_KERNEL);
- if (!new_table) {
- p->error = -ENOMEM;
- __set_current_state(TASK_RUNNING);
- return;
- }
- }
- }
- if (new_table) {
+ 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;
+ }
new_table->entry = new_table->entries;
new_table->next = table;
p->table = new_table;
@@ -110,6 +113,48 @@ void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table
#define BITS(fds, n) (*__IN(fds, n)|*__OUT(fds, n)|*__EX(fds, n))
+static int max_select_fd(unsigned long n, fd_set_bits *fds)
+{
+ unsigned long *open_fds;
+ unsigned long set;
+ int max;
+
+ /* handle last in-complete long-word first */
+ set = ~(~0UL << (n & (__NFDBITS-1)));
+ n /= __NFDBITS;
+ open_fds = current->files->open_fds->fds_bits+n;
+ max = 0;
+ if (set) {
+ set &= BITS(fds, n);
+ if (set) {
+ if (!(set & ~*open_fds))
+ goto get_max;
+ return -EBADF;
+ }
+ }
+ while (n) {
+ open_fds--;
+ n--;
+ set = BITS(fds, n);
+ if (!set)
+ continue;
+ if (set & ~*open_fds)
+ return -EBADF;
+ if (max)
+ continue;
+get_max:
+ do {
+ max++;
+ set >>= 1;
+ } while (set);
+ max += n * __NFDBITS;
+ }
+
+ return max;
+}
+
+#define BIT(i) (1UL << ((i)&(__NFDBITS-1)))
+#define MEM(i,m) ((m)+(unsigned)(i)/__NFDBITS)
#define ISSET(i,m) (((i)&*(m)) != 0)
#define SET(i,m) (*(m) |= (i))
@@ -120,106 +165,84 @@ void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table
int do_select(int n, fd_set_bits *fds, long *timeout)
{
poll_table table, *wait;
- int retval, off, maxoff;
+ int retval, i, off;
long __timeout = *timeout;
+ read_lock(&current->files->file_lock);
+ retval = max_select_fd(n, fds);
+ read_unlock(&current->files->file_lock);
+
+ if (retval < 0)
+ return retval;
+ n = retval;
+
poll_initwait(&table);
wait = &table;
if (!__timeout)
wait = NULL;
-
retval = 0;
- maxoff = FDS_LONGS(n);
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
- for (off = 0; off <= maxoff; off++) {
- unsigned long val = BITS(fds, off);
-
- while (val) {
- int k = ffz(~val), index;
- unsigned long mask, bit;
- struct file *file;
-
- bit = (1UL << k);
- val &= ~bit;
-
- index = off*BITS_PER_LONG + k;
- if (index >= n)
- break;
-
- file = fget(index);
- mask = POLLNVAL;
- if (file) {
- mask = DEFAULT_POLLMASK;
- if (file->f_op && file->f_op->poll)
- mask = file->f_op->poll(file, wait);
- fput(file);
- } else {
- /* This error will shadow all other results.
- * This matches previous linux behaviour */
- retval = -EBADF;
- goto out;
- }
- if ((mask & POLLIN_SET) && ISSET(bit, __IN(fds,off))) {
- SET(bit, __RES_IN(fds,off));
- retval++;
- wait = NULL;
- }
- if ((mask & POLLOUT_SET) && ISSET(bit,__OUT(fds,off))) {
- SET(bit, __RES_OUT(fds,off));
- retval++;
- wait = NULL;
- }
- if ((mask & POLLEX_SET) && ISSET(bit, __EX(fds,off))) {
- SET(bit, __RES_EX(fds,off));
- retval++;
- wait = NULL;
- }
+ for (i = 0 ; i < n; i++) {
+ unsigned long bit = BIT(i);
+ unsigned long mask;
+ struct file *file;
+
+ off = i / __NFDBITS;
+ if (!(bit & BITS(fds, off)))
+ continue;
+ file = fget(i);
+ mask = POLLNVAL;
+ if (file) {
+ mask = DEFAULT_POLLMASK;
+ if (file->f_op && file->f_op->poll)
+ mask = file->f_op->poll(file, wait);
+ fput(file);
+ }
+ if ((mask & POLLIN_SET) && ISSET(bit, __IN(fds,off))) {
+ SET(bit, __RES_IN(fds,off));
+ retval++;
+ wait = NULL;
+ }
+ if ((mask & POLLOUT_SET) && ISSET(bit, __OUT(fds,off))) {
+ SET(bit, __RES_OUT(fds,off));
+ retval++;
+ wait = NULL;
+ }
+ if ((mask & POLLEX_SET) && ISSET(bit, __EX(fds,off))) {
+ SET(bit, __RES_EX(fds,off));
+ retval++;
+ wait = NULL;
}
}
-
wait = NULL;
if (retval || !__timeout || signal_pending(current))
break;
- if (table.error) {
+ if(table.error) {
retval = table.error;
break;
}
__timeout = schedule_timeout(__timeout);
}
-
-out:
current->state = TASK_RUNNING;
poll_freewait(&table);
/*
- * Update the caller timeout.
+ * Up-to-date the caller timeout.
*/
*timeout = __timeout;
return retval;
}
-/*
- * We do a VERIFY_WRITE here even though we are only reading this time:
- * we'll write to it eventually..
- */
+static void *select_bits_alloc(int size)
+{
+ return kmalloc(6 * size, GFP_KERNEL);
+}
-static int get_fd_set(unsigned long nr, void *ufdset, unsigned long *fdset)
+static void select_bits_free(void *bits, int size)
{
- unsigned long rounded = FDS_BYTES(nr);
- if (ufdset) {
- int error = verify_area(VERIFY_WRITE, ufdset, rounded);
- if (!error && __copy_from_user(fdset, ufdset, rounded))
- error = -EFAULT;
- if (nr % __NFDBITS) {
- unsigned long mask = ~(~0UL << (nr % __NFDBITS));
- fdset[nr/__NFDBITS] &= mask;
- }
- return error;
- }
- memset(fdset, 0, rounded);
- return 0;
+ kfree(bits);
}
/*
@@ -237,10 +260,9 @@ asmlinkage long
sys_select(int n, fd_set *inp, fd_set *outp, fd_set *exp, struct timeval *tvp)
{
fd_set_bits fds;
- unsigned long *bits;
+ char *bits;
long timeout;
int ret, size, max_fdset;
- unsigned long stack_bits[FDS_LONGS(FAST_SELECT_MAX) * 6];
timeout = MAX_SCHEDULE_TIMEOUT;
if (tvp) {
@@ -275,27 +297,25 @@ sys_select(int n, fd_set *inp, fd_set *outp, fd_set *exp, struct timeval *tvp)
* since we used fdset we need to allocate memory in units of
* long-words.
*/
- size = FDS_LONGS(n);
- bits = stack_bits;
- if (n >= FAST_SELECT_MAX) {
- ret = -ENOMEM;
- bits = kmalloc(sizeof(unsigned long)*6*size, GFP_KERNEL);
- if (!bits)
- goto out_nofds;
- }
-
- fds.in = bits;
- fds.out = bits + size;
- fds.ex = bits + 2*size;
- fds.res_in = bits + 3*size;
- fds.res_out = bits + 4*size;
- fds.res_ex = bits + 5*size;
+ ret = -ENOMEM;
+ size = FDS_BYTES(n);
+ bits = select_bits_alloc(size);
+ if (!bits)
+ goto out_nofds;
+ fds.in = (unsigned long *) bits;
+ fds.out = (unsigned long *) (bits + size);
+ fds.ex = (unsigned long *) (bits + 2*size);
+ fds.res_in = (unsigned long *) (bits + 3*size);
+ fds.res_out = (unsigned long *) (bits + 4*size);
+ fds.res_ex = (unsigned long *) (bits + 5*size);
if ((ret = get_fd_set(n, inp, fds.in)) ||
(ret = get_fd_set(n, outp, fds.out)) ||
(ret = get_fd_set(n, exp, fds.ex)))
goto out;
- memset(fds.res_in, 0, 3*size);
+ zero_fd_set(n, fds.res_in);
+ zero_fd_set(n, fds.res_out);
+ zero_fd_set(n, fds.res_ex);
ret = do_select(n, &fds, &timeout);
@@ -306,8 +326,8 @@ sys_select(int n, fd_set *inp, fd_set *outp, fd_set *exp, struct timeval *tvp)
usec = timeout % HZ;
usec *= (1000000/HZ);
}
- __put_user(sec, &tvp->tv_sec);
- __put_user(usec, &tvp->tv_usec);
+ put_user(sec, &tvp->tv_sec);
+ put_user(usec, &tvp->tv_usec);
}
if (ret < 0)
@@ -324,10 +344,8 @@ sys_select(int n, fd_set *inp, fd_set *outp, fd_set *exp, struct timeval *tvp)
set_fd_set(n, exp, fds.res_ex);
out:
- if (n >= FAST_SELECT_MAX)
- kfree(bits);
+ select_bits_free(bits, size);
out_nofds:
-
return ret;
}
@@ -392,42 +410,12 @@ static int do_poll(unsigned int nfds, unsigned int nchunks, unsigned int nleft,
return count;
}
-static int fast_poll(poll_table *table, poll_table *wait, struct pollfd *ufds,
- unsigned int nfds, long timeout)
-{
- poll_table *pt = wait;
- struct pollfd fds[FAST_POLL_MAX];
- int count, i;
-
- if (copy_from_user(fds, ufds, nfds * sizeof(struct pollfd)))
- return -EFAULT;
- for (;;) {
- set_current_state(TASK_INTERRUPTIBLE);
- count = 0;
- do_pollfd(nfds, fds, &pt, &count);
- pt = NULL;
- if (count || !timeout || signal_pending(current))
- break;
- count = wait->error;
- if (count)
- break;
- timeout = schedule_timeout(timeout);
- }
- current->state = TASK_RUNNING;
- for (i = 0; i < nfds; i++)
- __put_user(fds[i].revents, &ufds[i].revents);
- poll_freewait(table);
- if (!count && signal_pending(current))
- return -EINTR;
- return count;
-}
-
asmlinkage long sys_poll(struct pollfd * ufds, unsigned int nfds, long timeout)
{
- int i, j, err, fdcount;
+ int i, j, fdcount, err;
struct pollfd **fds;
poll_table table, *wait;
- int nchunks, nleft;
+ int nchunks, nleft;
/* Do a sanity check on nfds ... */
if (nfds > NR_OPEN)
@@ -441,45 +429,43 @@ asmlinkage long sys_poll(struct pollfd * ufds, unsigned int nfds, long timeout)
timeout = MAX_SCHEDULE_TIMEOUT;
}
-
poll_initwait(&table);
wait = &table;
if (!timeout)
wait = NULL;
- if (nfds < FAST_POLL_MAX)
- return fast_poll(&table, wait, ufds, nfds, timeout);
-
err = -ENOMEM;
- fds = (struct pollfd **)kmalloc(
- (1 + (nfds - 1) / POLLFD_PER_PAGE) * sizeof(struct pollfd *),
- GFP_KERNEL);
- if (fds == NULL)
- goto out;
-
+ fds = NULL;
+ if (nfds != 0) {
+ fds = (struct pollfd **)kmalloc(
+ (1 + (nfds - 1) / POLLFD_PER_PAGE) * sizeof(struct pollfd *),
+ GFP_KERNEL);
+ if (fds == NULL)
+ goto out;
+ }
+
nchunks = 0;
nleft = nfds;
- while (nleft > POLLFD_PER_PAGE) {
+ while (nleft > POLLFD_PER_PAGE) { /* allocate complete PAGE_SIZE chunks */
fds[nchunks] = (struct pollfd *)__get_free_page(GFP_KERNEL);
if (fds[nchunks] == NULL)
goto out_fds;
nchunks++;
nleft -= POLLFD_PER_PAGE;
}
- if (nleft) {
+ if (nleft) { /* allocate last PAGE_SIZE chunk, only nleft elements used */
fds[nchunks] = (struct pollfd *)__get_free_page(GFP_KERNEL);
if (fds[nchunks] == NULL)
goto out_fds;
- }
-
+ }
+
err = -EFAULT;
for (i=0; i < nchunks; i++)
if (copy_from_user(fds[i], ufds + i*POLLFD_PER_PAGE, PAGE_SIZE))
goto out_fds1;
-
if (nleft) {
if (copy_from_user(fds[nchunks], ufds + nchunks*POLLFD_PER_PAGE,
- nleft * sizeof(struct pollfd)))
+ nleft * sizeof(struct pollfd)))
goto out_fds1;
}
@@ -503,7 +489,8 @@ out_fds1:
out_fds:
for (i=0; i < nchunks; i++)
free_page((unsigned long)(fds[i]));
- kfree(fds);
+ if (nfds != 0)
+ kfree(fds);
out:
poll_freewait(&table);
return err;
diff --git a/include/linux/poll.h b/include/linux/poll.h
index 86b1ee2d3eb3..796aac51388a 100644
--- a/include/linux/poll.h
+++ b/include/linux/poll.h
@@ -10,32 +10,13 @@
#include <linux/mm.h>
#include <asm/uaccess.h>
-#define POLL_INLINE_BYTES 256
-#define FAST_SELECT_MAX 128
-#define FAST_POLL_MAX 128
-#define POLL_INLINE_ENTRIES (1+(POLL_INLINE_BYTES / sizeof(struct poll_table_entry)))
-
-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;
- struct poll_table_entry entries[0];
-};
+struct poll_table_page;
typedef struct poll_table_struct {
int error;
struct poll_table_page * table;
- struct poll_table_page inline_page;
- struct poll_table_entry inline_table[POLL_INLINE_ENTRIES];
} poll_table;
-#define POLL_INLINE_TABLE_LEN (sizeof(poll_table) - offsetof(poll_table, inline_page))
-
extern void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p);
static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
@@ -49,7 +30,6 @@ static inline void poll_initwait(poll_table* pt)
pt->error = 0;
pt->table = NULL;
}
-
extern void poll_freewait(poll_table* pt);
@@ -69,6 +49,27 @@ typedef struct {
#define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
#define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))
+/*
+ * We do a VERIFY_WRITE here even though we are only reading this time:
+ * we'll write to it eventually..
+ *
+ * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
+ */
+static inline
+int get_fd_set(unsigned long nr, void *ufdset, unsigned long *fdset)
+{
+ nr = FDS_BYTES(nr);
+ if (ufdset) {
+ int error;
+ error = verify_area(VERIFY_WRITE, ufdset, nr);
+ if (!error && __copy_from_user(fdset, ufdset, nr))
+ error = -EFAULT;
+ return error;
+ }
+ memset(fdset, 0, nr);
+ return 0;
+}
+
static inline
void set_fd_set(unsigned long nr, void *ufdset, unsigned long *fdset)
{
@@ -76,6 +77,12 @@ void set_fd_set(unsigned long nr, void *ufdset, unsigned long *fdset)
__copy_to_user(ufdset, fdset, FDS_BYTES(nr));
}
+static inline
+void zero_fd_set(unsigned long nr, unsigned long *fdset)
+{
+ memset(fdset, 0, FDS_BYTES(nr));
+}
+
extern int do_select(int n, fd_set_bits *fds, long *timeout);
#endif /* KERNEL */