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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/select.c
downloadlinux-linaro-stable-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'fs/select.c')
-rw-r--r--fs/select.c534
1 files changed, 534 insertions, 0 deletions
diff --git a/fs/select.c b/fs/select.c
new file mode 100644
index 000000000000..25b1ccac2f2c
--- /dev/null
+++ b/fs/select.c
@@ -0,0 +1,534 @@
+/*
+ * This file contains the procedures for the handling of select and poll
+ *
+ * Created for Linux based loosely upon Mathius Lattner's minix
+ * patches by Peter MacDonald. Heavily edited by Linus.
+ *
+ * 4 February 1994
+ * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
+ * flag set in its personality we do *not* modify the given timeout
+ * parameter to reflect time remaining.
+ *
+ * 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).
+ */
+
+#include <linux/syscalls.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/poll.h>
+#include <linux/personality.h> /* for STICKY_TIMEOUTS */
+#include <linux/file.h>
+#include <linux/fs.h>
+
+#include <asm/uaccess.h>
+
+#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
+ * follow, but it should be free of race-conditions, and it's practical. If you
+ * understand what I'm doing here, then you understand how the linux
+ * sleep/wakeup mechanism works.
+ *
+ * Two very simple procedures, poll_wait() and poll_freewait() make all the
+ * work. poll_wait() is an inline-function defined in <linux/poll.h>,
+ * as all select/poll functions have to call it to add an entry to the
+ * poll table.
+ */
+void __pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *p);
+
+void poll_initwait(struct poll_wqueues *pwq)
+{
+ init_poll_funcptr(&pwq->pt, __pollwait);
+ pwq->error = 0;
+ pwq->table = NULL;
+}
+
+EXPORT_SYMBOL(poll_initwait);
+
+void poll_freewait(struct poll_wqueues *pwq)
+{
+ struct poll_table_page * p = pwq->table;
+ 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);
+ } while (entry > p->entries);
+ old = p;
+ p = p->next;
+ free_page((unsigned long) old);
+ }
+}
+
+EXPORT_SYMBOL(poll_freewait);
+
+void __pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *_p)
+{
+ struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
+ struct poll_table_page *table = p->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;
+ 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);
+ }
+}
+
+#define FDS_IN(fds, n) (fds->in + n)
+#define FDS_OUT(fds, n) (fds->out + n)
+#define FDS_EX(fds, n) (fds->ex + n)
+
+#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_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))
+
+#define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
+#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
+#define POLLEX_SET (POLLPRI)
+
+int do_select(int n, fd_set_bits *fds, long *timeout)
+{
+ struct poll_wqueues table;
+ poll_table *wait;
+ int retval, i;
+ long __timeout = *timeout;
+
+ spin_lock(&current->files->file_lock);
+ retval = max_select_fd(n, fds);
+ spin_unlock(&current->files->file_lock);
+
+ if (retval < 0)
+ return retval;
+ n = retval;
+
+ poll_initwait(&table);
+ wait = &table.pt;
+ if (!__timeout)
+ wait = NULL;
+ retval = 0;
+ for (;;) {
+ unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ inp = fds->in; outp = fds->out; exp = fds->ex;
+ rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
+
+ for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
+ unsigned long in, out, ex, all_bits, bit = 1, mask, j;
+ unsigned long res_in = 0, res_out = 0, res_ex = 0;
+ struct file_operations *f_op = NULL;
+ struct file *file = NULL;
+
+ in = *inp++; out = *outp++; ex = *exp++;
+ all_bits = in | out | ex;
+ if (all_bits == 0) {
+ i += __NFDBITS;
+ continue;
+ }
+
+ for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
+ if (i >= n)
+ break;
+ if (!(bit & all_bits))
+ continue;
+ file = fget(i);
+ if (file) {
+ f_op = file->f_op;
+ mask = DEFAULT_POLLMASK;
+ if (f_op && f_op->poll)
+ mask = (*f_op->poll)(file, retval ? NULL : wait);
+ fput(file);
+ if ((mask & POLLIN_SET) && (in & bit)) {
+ res_in |= bit;
+ retval++;
+ }
+ if ((mask & POLLOUT_SET) && (out & bit)) {
+ res_out |= bit;
+ retval++;
+ }
+ if ((mask & POLLEX_SET) && (ex & bit)) {
+ res_ex |= bit;
+ retval++;
+ }
+ }
+ cond_resched();
+ }
+ if (res_in)
+ *rinp = res_in;
+ if (res_out)
+ *routp = res_out;
+ if (res_ex)
+ *rexp = res_ex;
+ }
+ wait = NULL;
+ if (retval || !__timeout || signal_pending(current))
+ break;
+ if(table.error) {
+ retval = table.error;
+ break;
+ }
+ __timeout = schedule_timeout(__timeout);
+ }
+ __set_current_state(TASK_RUNNING);
+
+ poll_freewait(&table);
+
+ /*
+ * Up-to-date the caller timeout.
+ */
+ *timeout = __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
+ * EINTR just for safety.
+ *
+ * Update: ERESTARTSYS breaks at least the xview clock binary, so
+ * I'm trying ERESTARTNOHAND which restart only when you want to.
+ */
+#define MAX_SELECT_SECONDS \
+ ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
+
+asmlinkage long
+sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, struct timeval __user *tvp)
+{
+ fd_set_bits fds;
+ char *bits;
+ long timeout;
+ int ret, size, max_fdset;
+
+ timeout = MAX_SCHEDULE_TIMEOUT;
+ if (tvp) {
+ time_t sec, usec;
+
+ if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp))
+ || __get_user(sec, &tvp->tv_sec)
+ || __get_user(usec, &tvp->tv_usec)) {
+ ret = -EFAULT;
+ goto out_nofds;
+ }
+
+ ret = -EINVAL;
+ if (sec < 0 || usec < 0)
+ goto out_nofds;
+
+ if ((unsigned long) sec < MAX_SELECT_SECONDS) {
+ timeout = ROUND_UP(usec, 1000000/HZ);
+ timeout += sec * (unsigned long) HZ;
+ }
+ }
+
+ ret = -EINVAL;
+ if (n < 0)
+ goto out_nofds;
+
+ /* max_fdset can increase, so grab it once to avoid race */
+ max_fdset = current->files->max_fdset;
+ if (n > max_fdset)
+ n = max_fdset;
+
+ /*
+ * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
+ * since we used fdset we need to allocate memory in units of
+ * long-words.
+ */
+ 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;
+ 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);
+
+ if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
+ time_t sec = 0, usec = 0;
+ if (timeout) {
+ sec = timeout / HZ;
+ usec = timeout % HZ;
+ usec *= (1000000/HZ);
+ }
+ put_user(sec, &tvp->tv_sec);
+ put_user(usec, &tvp->tv_usec);
+ }
+
+ if (ret < 0)
+ goto out;
+ if (!ret) {
+ ret = -ERESTARTNOHAND;
+ if (signal_pending(current))
+ goto out;
+ ret = 0;
+ }
+
+ if (set_fd_set(n, inp, fds.res_in) ||
+ set_fd_set(n, outp, fds.res_out) ||
+ set_fd_set(n, exp, fds.res_ex))
+ ret = -EFAULT;
+
+out:
+ select_bits_free(bits, size);
+out_nofds:
+ return ret;
+}
+
+struct poll_list {
+ struct poll_list *next;
+ int len;
+ struct pollfd entries[0];
+};
+
+#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
+
+static void do_pollfd(unsigned int num, struct pollfd * fdpage,
+ poll_table ** pwait, int *count)
+{
+ int i;
+
+ for (i = 0; i < num; i++) {
+ int fd;
+ unsigned int mask;
+ struct pollfd *fdp;
+
+ mask = 0;
+ fdp = fdpage+i;
+ fd = fdp->fd;
+ if (fd >= 0) {
+ struct file * file = fget(fd);
+ mask = POLLNVAL;
+ if (file != NULL) {
+ mask = DEFAULT_POLLMASK;
+ if (file->f_op && file->f_op->poll)
+ mask = file->f_op->poll(file, *pwait);
+ mask &= fdp->events | POLLERR | POLLHUP;
+ fput(file);
+ }
+ if (mask) {
+ *pwait = NULL;
+ (*count)++;
+ }
+ }
+ fdp->revents = mask;
+ }
+}
+
+static int do_poll(unsigned int nfds, struct poll_list *list,
+ struct poll_wqueues *wait, long timeout)
+{
+ int count = 0;
+ poll_table* pt = &wait->pt;
+
+ if (!timeout)
+ pt = NULL;
+
+ for (;;) {
+ struct poll_list *walk;
+ set_current_state(TASK_INTERRUPTIBLE);
+ walk = list;
+ while(walk != NULL) {
+ do_pollfd( walk->len, walk->entries, &pt, &count);
+ walk = walk->next;
+ }
+ pt = NULL;
+ if (count || !timeout || signal_pending(current))
+ break;
+ count = wait->error;
+ if (count)
+ break;
+ timeout = schedule_timeout(timeout);
+ }
+ __set_current_state(TASK_RUNNING);
+ return count;
+}
+
+asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long timeout)
+{
+ struct poll_wqueues table;
+ int fdcount, err;
+ unsigned int i;
+ struct poll_list *head;
+ struct poll_list *walk;
+
+ /* Do a sanity check on nfds ... */
+ if (nfds > current->files->max_fdset && nfds > OPEN_MAX)
+ return -EINVAL;
+
+ if (timeout) {
+ /* Careful about overflow in the intermediate values */
+ if ((unsigned long) timeout < MAX_SCHEDULE_TIMEOUT / HZ)
+ timeout = (unsigned long)(timeout*HZ+999)/1000+1;
+ else /* Negative or overflow */
+ timeout = MAX_SCHEDULE_TIMEOUT;
+ }
+
+ poll_initwait(&table);
+
+ head = NULL;
+ walk = NULL;
+ i = nfds;
+ 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;
+ pp->next=NULL;
+ pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
+ 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)) {
+ err = -EFAULT;
+ goto out_fds;
+ }
+ i -= pp->len;
+ }
+ fdcount = do_poll(nfds, head, &table, timeout);
+
+ /* OK, now copy the revents fields back to user space. */
+ walk = head;
+ err = -EFAULT;
+ while(walk != NULL) {
+ struct pollfd *fds = walk->entries;
+ int j;
+
+ for (j=0; j < walk->len; j++, ufds++) {
+ if(__put_user(fds[j].revents, &ufds->revents))
+ goto out_fds;
+ }
+ walk = walk->next;
+ }
+ err = fdcount;
+ if (!fdcount && signal_pending(current))
+ err = -EINTR;
+out_fds:
+ walk = head;
+ while(walk!=NULL) {
+ struct poll_list *pp = walk->next;
+ kfree(walk);
+ walk = pp;
+ }
+ poll_freewait(&table);
+ return err;
+}