fcntl.c

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    1 /*
    2  *  linux/fs/fcntl.c
    3  *
    4  *  Copyright (C) 1991, 1992  Linus Torvalds
    5  */
    6 
    7 #include <linux/syscalls.h>
    8 #include <linux/init.h>
    9 #include <linux/mm.h>
   10 #include <linux/fs.h>
   11 #include <linux/file.h>
   12 #include <linux/fdtable.h>
   13 #include <linux/capability.h>
   14 #include <linux/dnotify.h>
   15 #include <linux/slab.h>
   16 #include <linux/module.h>
   17 #include <linux/pipe_fs_i.h>
   18 #include <linux/security.h>
   19 #include <linux/ptrace.h>
   20 #include <linux/signal.h>
   21 #include <linux/rcupdate.h>
   22 #include <linux/pid_namespace.h>
   23 #include <linux/user_namespace.h>
   24 
   25 #include <asm/poll.h>
   26 #include <asm/siginfo.h>
   27 #include <asm/uaccess.h>
   28 
   29 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
   30 
   31 static int setfl(int fd, struct file * filp, unsigned long arg)
   32 {
   33         struct inode * inode = filp->f_path.dentry->d_inode;
   34         int error = 0;
   35 
   36         /*
   37          * O_APPEND cannot be cleared if the file is marked as append-only
   38          * and the file is open for write.
   39          */
   40         if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
   41                 return -EPERM;
   42 
   43         /* O_NOATIME can only be set by the owner or superuser */
   44         if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
   45                 if (!inode_owner_or_capable(inode))
   46                         return -EPERM;
   47 
   48         /* required for strict SunOS emulation */
   49         if (O_NONBLOCK != O_NDELAY)
   50                if (arg & O_NDELAY)
   51                    arg |= O_NONBLOCK;
   52 
   53         if (arg & O_DIRECT) {
   54                 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
   55                         !filp->f_mapping->a_ops->direct_IO)
   56                                 return -EINVAL;
   57         }
   58 
   59         if (filp->f_op && filp->f_op->check_flags)
   60                 error = filp->f_op->check_flags(arg);
   61         if (error)
   62                 return error;
   63 
   64         /*
   65          * ->fasync() is responsible for setting the FASYNC bit.
   66          */
   67         if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
   68                         filp->f_op->fasync) {
   69                 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
   70                 if (error < 0)
   71                         goto out;
   72                 if (error > 0)
   73                         error = 0;
   74         }
   75         spin_lock(&filp->f_lock);
   76         filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
   77         spin_unlock(&filp->f_lock);
   78 
   79  out:
   80         return error;
   81 }
   82 
   83 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
   84                      int force)
   85 {
   86         write_lock_irq(&filp->f_owner.lock);
   87         if (force || !filp->f_owner.pid) {
   88                 put_pid(filp->f_owner.pid);
   89                 filp->f_owner.pid = get_pid(pid);
   90                 filp->f_owner.pid_type = type;
   91 
   92                 if (pid) {
   93                         const struct cred *cred = current_cred();
   94                         filp->f_owner.uid = cred->uid;
   95                         filp->f_owner.euid = cred->euid;
   96                 }
   97         }
   98         write_unlock_irq(&filp->f_owner.lock);
   99 }
  100 
  101 int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
  102                 int force)
  103 {
  104         int err;
  105 
  106         err = security_file_set_fowner(filp);
  107         if (err)
  108                 return err;
  109 
  110         f_modown(filp, pid, type, force);
  111         return 0;
  112 }
  113 EXPORT_SYMBOL(__f_setown);
  114 
  115 int f_setown(struct file *filp, unsigned long arg, int force)
  116 {
  117         enum pid_type type;
  118         struct pid *pid;
  119         int who = arg;
  120         int result;
  121         type = PIDTYPE_PID;
  122         if (who < 0) {
  123                 type = PIDTYPE_PGID;
  124                 who = -who;
  125         }
  126         rcu_read_lock();
  127         pid = find_vpid(who);
  128         result = __f_setown(filp, pid, type, force);
  129         rcu_read_unlock();
  130         return result;
  131 }
  132 EXPORT_SYMBOL(f_setown);
  133 
  134 void f_delown(struct file *filp)
  135 {
  136         f_modown(filp, NULL, PIDTYPE_PID, 1);
  137 }
  138 
  139 pid_t f_getown(struct file *filp)
  140 {
  141         pid_t pid;
  142         read_lock(&filp->f_owner.lock);
  143         pid = pid_vnr(filp->f_owner.pid);
  144         if (filp->f_owner.pid_type == PIDTYPE_PGID)
  145                 pid = -pid;
  146         read_unlock(&filp->f_owner.lock);
  147         return pid;
  148 }
  149 
  150 static int f_setown_ex(struct file *filp, unsigned long arg)
  151 {
  152         struct f_owner_ex __user *owner_p = (void __user *)arg;
  153         struct f_owner_ex owner;
  154         struct pid *pid;
  155         int type;
  156         int ret;
  157 
  158         ret = copy_from_user(&owner, owner_p, sizeof(owner));
  159         if (ret)
  160                 return -EFAULT;
  161 
  162         switch (owner.type) {
  163         case F_OWNER_TID:
  164                 type = PIDTYPE_MAX;
  165                 break;
  166 
  167         case F_OWNER_PID:
  168                 type = PIDTYPE_PID;
  169                 break;
  170 
  171         case F_OWNER_PGRP:
  172                 type = PIDTYPE_PGID;
  173                 break;
  174 
  175         default:
  176                 return -EINVAL;
  177         }
  178 
  179         rcu_read_lock();
  180         pid = find_vpid(owner.pid);
  181         if (owner.pid && !pid)
  182                 ret = -ESRCH;
  183         else
  184                 ret = __f_setown(filp, pid, type, 1);
  185         rcu_read_unlock();
  186 
  187         return ret;
  188 }
  189 
  190 static int f_getown_ex(struct file *filp, unsigned long arg)
  191 {
  192         struct f_owner_ex __user *owner_p = (void __user *)arg;
  193         struct f_owner_ex owner;
  194         int ret = 0;
  195 
  196         read_lock(&filp->f_owner.lock);
  197         owner.pid = pid_vnr(filp->f_owner.pid);
  198         switch (filp->f_owner.pid_type) {
  199         case PIDTYPE_MAX:
  200                 owner.type = F_OWNER_TID;
  201                 break;
  202 
  203         case PIDTYPE_PID:
  204                 owner.type = F_OWNER_PID;
  205                 break;
  206 
  207         case PIDTYPE_PGID:
  208                 owner.type = F_OWNER_PGRP;
  209                 break;
  210 
  211         default:
  212                 WARN_ON(1);
  213                 ret = -EINVAL;
  214                 break;
  215         }
  216         read_unlock(&filp->f_owner.lock);
  217 
  218         if (!ret) {
  219                 ret = copy_to_user(owner_p, &owner, sizeof(owner));
  220                 if (ret)
  221                         ret = -EFAULT;
  222         }
  223         return ret;
  224 }
  225 
  226 #ifdef CONFIG_CHECKPOINT_RESTORE
  227 static int f_getowner_uids(struct file *filp, unsigned long arg)
  228 {
  229         struct user_namespace *user_ns = current_user_ns();
  230         uid_t __user *dst = (void __user *)arg;
  231         uid_t src[2];
  232         int err;
  233 
  234         read_lock(&filp->f_owner.lock);
  235         src[0] = from_kuid(user_ns, filp->f_owner.uid);
  236         src[1] = from_kuid(user_ns, filp->f_owner.euid);
  237         read_unlock(&filp->f_owner.lock);
  238 
  239         err  = put_user(src[0], &dst[0]);
  240         err |= put_user(src[1], &dst[1]);
  241 
  242         return err;
  243 }
  244 #else
  245 static int f_getowner_uids(struct file *filp, unsigned long arg)
  246 {
  247         return -EINVAL;
  248 }
  249 #endif
  250 
  251 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
  252                 struct file *filp)
  253 {
  254         long err = -EINVAL;
  255 
  256         switch (cmd) {
  257         case F_DUPFD:
  258                 err = f_dupfd(arg, filp, 0);
  259                 break;
  260         case F_DUPFD_CLOEXEC:
  261                 err = f_dupfd(arg, filp, O_CLOEXEC);
  262                 break;
  263         case F_GETFD:
  264                 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
  265                 break;
  266         case F_SETFD:
  267                 err = 0;
  268                 set_close_on_exec(fd, arg & FD_CLOEXEC);
  269                 break;
  270         case F_GETFL:
  271                 err = filp->f_flags;
  272                 break;
  273         case F_SETFL:
  274                 err = setfl(fd, filp, arg);
  275                 break;
  276         case F_GETLK:
  277                 err = fcntl_getlk(filp, (struct flock __user *) arg);
  278                 break;
  279         case F_SETLK:
  280         case F_SETLKW:
  281                 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
  282                 break;
  283         case F_GETOWN:
  284                 /*
  285                  * XXX If f_owner is a process group, the
  286                  * negative return value will get converted
  287                  * into an error.  Oops.  If we keep the
  288                  * current syscall conventions, the only way
  289                  * to fix this will be in libc.
  290                  */
  291                 err = f_getown(filp);
  292                 force_successful_syscall_return();
  293                 break;
  294         case F_SETOWN:
  295                 err = f_setown(filp, arg, 1);
  296                 break;
  297         case F_GETOWN_EX:
  298                 err = f_getown_ex(filp, arg);
  299                 break;
  300         case F_SETOWN_EX:
  301                 err = f_setown_ex(filp, arg);
  302                 break;
  303         case F_GETOWNER_UIDS:
  304                 err = f_getowner_uids(filp, arg);
  305                 break;
  306         case F_GETSIG:
  307                 err = filp->f_owner.signum;
  308                 break;
  309         case F_SETSIG:
  310                 /* arg == 0 restores default behaviour. */
  311                 if (!valid_signal(arg)) {
  312                         break;
  313                 }
  314                 err = 0;
  315                 filp->f_owner.signum = arg;
  316                 break;
  317         case F_GETLEASE:
  318                 err = fcntl_getlease(filp);
  319                 break;
  320         case F_SETLEASE:
  321                 err = fcntl_setlease(fd, filp, arg);
  322                 break;
  323         case F_NOTIFY:
  324                 err = fcntl_dirnotify(fd, filp, arg);
  325                 break;
  326         case F_SETPIPE_SZ:
  327         case F_GETPIPE_SZ:
  328                 err = pipe_fcntl(filp, cmd, arg);
  329                 break;
  330         default:
  331                 break;
  332         }
  333         return err;
  334 }
  335 
  336 static int check_fcntl_cmd(unsigned cmd)
  337 {
  338         switch (cmd) {
  339         case F_DUPFD:
  340         case F_DUPFD_CLOEXEC:
  341         case F_GETFD:
  342         case F_SETFD:
  343         case F_GETFL:
  344                 return 1;
  345         }
  346         return 0;
  347 }
  348 
  349 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
  350 {       
  351         struct fd f = fdget_raw(fd);
  352         long err = -EBADF;
  353 
  354         if (!f.file)
  355                 goto out;
  356 
  357         if (unlikely(f.file->f_mode & FMODE_PATH)) {
  358                 if (!check_fcntl_cmd(cmd))
  359                         goto out1;
  360         }
  361 
  362         err = security_file_fcntl(f.file, cmd, arg);
  363         if (!err)
  364                 err = do_fcntl(fd, cmd, arg, f.file);
  365 
  366 out1:
  367         fdput(f);
  368 out:
  369         return err;
  370 }
  371 
  372 #if BITS_PER_LONG == 32
  373 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
  374                 unsigned long, arg)
  375 {       
  376         struct fd f = fdget_raw(fd);
  377         long err = -EBADF;
  378 
  379         if (!f.file)
  380                 goto out;
  381 
  382         if (unlikely(f.file->f_mode & FMODE_PATH)) {
  383                 if (!check_fcntl_cmd(cmd))
  384                         goto out1;
  385         }
  386 
  387         err = security_file_fcntl(f.file, cmd, arg);
  388         if (err)
  389                 goto out1;
  390         
  391         switch (cmd) {
  392                 case F_GETLK64:
  393                         err = fcntl_getlk64(f.file, (struct flock64 __user *) arg);
  394                         break;
  395                 case F_SETLK64:
  396                 case F_SETLKW64:
  397                         err = fcntl_setlk64(fd, f.file, cmd,
  398                                         (struct flock64 __user *) arg);
  399                         break;
  400                 default:
  401                         err = do_fcntl(fd, cmd, arg, f.file);
  402                         break;
  403         }
  404 out1:
  405         fdput(f);
  406 out:
  407         return err;
  408 }
  409 #endif
  410 
  411 /* Table to convert sigio signal codes into poll band bitmaps */
  412 
  413 static const long band_table[NSIGPOLL] = {
  414         POLLIN | POLLRDNORM,                    /* POLL_IN */
  415         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
  416         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
  417         POLLERR,                                /* POLL_ERR */
  418         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
  419         POLLHUP | POLLERR                       /* POLL_HUP */
  420 };
  421 
  422 static inline int sigio_perm(struct task_struct *p,
  423                              struct fown_struct *fown, int sig)
  424 {
  425         const struct cred *cred;
  426         int ret;
  427 
  428         rcu_read_lock();
  429         cred = __task_cred(p);
  430         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
  431                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
  432                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
  433                !security_file_send_sigiotask(p, fown, sig));
  434         rcu_read_unlock();
  435         return ret;
  436 }
  437 
  438 static void send_sigio_to_task(struct task_struct *p,
  439                                struct fown_struct *fown,
  440                                int fd, int reason, int group)
  441 {
  442         /*
  443          * F_SETSIG can change ->signum lockless in parallel, make
  444          * sure we read it once and use the same value throughout.
  445          */
  446         int signum = ACCESS_ONCE(fown->signum);
  447 
  448         if (!sigio_perm(p, fown, signum))
  449                 return;
  450 
  451         switch (signum) {
  452                 siginfo_t si;
  453                 default:
  454                         /* Queue a rt signal with the appropriate fd as its
  455                            value.  We use SI_SIGIO as the source, not 
  456                            SI_KERNEL, since kernel signals always get 
  457                            delivered even if we can't queue.  Failure to
  458                            queue in this case _should_ be reported; we fall
  459                            back to SIGIO in that case. --sct */
  460                         si.si_signo = signum;
  461                         si.si_errno = 0;
  462                         si.si_code  = reason;
  463                         /* Make sure we are called with one of the POLL_*
  464                            reasons, otherwise we could leak kernel stack into
  465                            userspace.  */
  466                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
  467                         if (reason - POLL_IN >= NSIGPOLL)
  468                                 si.si_band  = ~0L;
  469                         else
  470                                 si.si_band = band_table[reason - POLL_IN];
  471                         si.si_fd    = fd;
  472                         if (!do_send_sig_info(signum, &si, p, group))
  473                                 break;
  474                 /* fall-through: fall back on the old plain SIGIO signal */
  475                 case 0:
  476                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
  477         }
  478 }
  479 
  480 void send_sigio(struct fown_struct *fown, int fd, int band)
  481 {
  482         struct task_struct *p;
  483         enum pid_type type;
  484         struct pid *pid;
  485         int group = 1;
  486         
  487         read_lock(&fown->lock);
  488 
  489         type = fown->pid_type;
  490         if (type == PIDTYPE_MAX) {
  491                 group = 0;
  492                 type = PIDTYPE_PID;
  493         }
  494 
  495         pid = fown->pid;
  496         if (!pid)
  497                 goto out_unlock_fown;
  498         
  499         read_lock(&tasklist_lock);
  500         do_each_pid_task(pid, type, p) {
  501                 send_sigio_to_task(p, fown, fd, band, group);
  502         } while_each_pid_task(pid, type, p);
  503         read_unlock(&tasklist_lock);
  504  out_unlock_fown:
  505         read_unlock(&fown->lock);
  506 }
  507 
  508 static void send_sigurg_to_task(struct task_struct *p,
  509                                 struct fown_struct *fown, int group)
  510 {
  511         if (sigio_perm(p, fown, SIGURG))
  512                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
  513 }
  514 
  515 int send_sigurg(struct fown_struct *fown)
  516 {
  517         struct task_struct *p;
  518         enum pid_type type;
  519         struct pid *pid;
  520         int group = 1;
  521         int ret = 0;
  522         
  523         read_lock(&fown->lock);
  524 
  525         type = fown->pid_type;
  526         if (type == PIDTYPE_MAX) {
  527                 group = 0;
  528                 type = PIDTYPE_PID;
  529         }
  530 
  531         pid = fown->pid;
  532         if (!pid)
  533                 goto out_unlock_fown;
  534 
  535         ret = 1;
  536         
  537         read_lock(&tasklist_lock);
  538         do_each_pid_task(pid, type, p) {
  539                 send_sigurg_to_task(p, fown, group);
  540         } while_each_pid_task(pid, type, p);
  541         read_unlock(&tasklist_lock);
  542  out_unlock_fown:
  543         read_unlock(&fown->lock);
  544         return ret;
  545 }
  546 
  547 static DEFINE_SPINLOCK(fasync_lock);
  548 static struct kmem_cache *fasync_cache __read_mostly;
  549 
  550 static void fasync_free_rcu(struct rcu_head *head)
  551 {
  552         kmem_cache_free(fasync_cache,
  553                         container_of(head, struct fasync_struct, fa_rcu));
  554 }
  555 
  556 /*
  557  * Remove a fasync entry. If successfully removed, return
  558  * positive and clear the FASYNC flag. If no entry exists,
  559  * do nothing and return 0.
  560  *
  561  * NOTE! It is very important that the FASYNC flag always
  562  * match the state "is the filp on a fasync list".
  563  *
  564  */
  565 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
  566 {
  567         struct fasync_struct *fa, **fp;
  568         int result = 0;
  569 
  570         spin_lock(&filp->f_lock);
  571         spin_lock(&fasync_lock);
  572         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
  573                 if (fa->fa_file != filp)
  574                         continue;
  575 
  576                 spin_lock_irq(&fa->fa_lock);
  577                 fa->fa_file = NULL;
  578                 spin_unlock_irq(&fa->fa_lock);
  579 
  580                 *fp = fa->fa_next;
  581                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
  582                 filp->f_flags &= ~FASYNC;
  583                 result = 1;
  584                 break;
  585         }
  586         spin_unlock(&fasync_lock);
  587         spin_unlock(&filp->f_lock);
  588         return result;
  589 }
  590 
  591 struct fasync_struct *fasync_alloc(void)
  592 {
  593         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
  594 }
  595 
  596 /*
  597  * NOTE! This can be used only for unused fasync entries:
  598  * entries that actually got inserted on the fasync list
  599  * need to be released by rcu - see fasync_remove_entry.
  600  */
  601 void fasync_free(struct fasync_struct *new)
  602 {
  603         kmem_cache_free(fasync_cache, new);
  604 }
  605 
  606 /*
  607  * Insert a new entry into the fasync list.  Return the pointer to the
  608  * old one if we didn't use the new one.
  609  *
  610  * NOTE! It is very important that the FASYNC flag always
  611  * match the state "is the filp on a fasync list".
  612  */
  613 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
  614 {
  615         struct fasync_struct *fa, **fp;
  616 
  617         spin_lock(&filp->f_lock);
  618         spin_lock(&fasync_lock);
  619         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
  620                 if (fa->fa_file != filp)
  621                         continue;
  622 
  623                 spin_lock_irq(&fa->fa_lock);
  624                 fa->fa_fd = fd;
  625                 spin_unlock_irq(&fa->fa_lock);
  626                 goto out;
  627         }
  628 
  629         spin_lock_init(&new->fa_lock);
  630         new->magic = FASYNC_MAGIC;
  631         new->fa_file = filp;
  632         new->fa_fd = fd;
  633         new->fa_next = *fapp;
  634         rcu_assign_pointer(*fapp, new);
  635         filp->f_flags |= FASYNC;
  636 
  637 out:
  638         spin_unlock(&fasync_lock);
  639         spin_unlock(&filp->f_lock);
  640         return fa;
  641 }
  642 
  643 /*
  644  * Add a fasync entry. Return negative on error, positive if
  645  * added, and zero if did nothing but change an existing one.
  646  */
  647 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
  648 {
  649         struct fasync_struct *new;
  650 
  651         new = fasync_alloc();
  652         if (!new)
  653                 return -ENOMEM;
  654 
  655         /*
  656          * fasync_insert_entry() returns the old (update) entry if
  657          * it existed.
  658          *
  659          * So free the (unused) new entry and return 0 to let the
  660          * caller know that we didn't add any new fasync entries.
  661          */
  662         if (fasync_insert_entry(fd, filp, fapp, new)) {
  663                 fasync_free(new);
  664                 return 0;
  665         }
  666 
  667         return 1;
  668 }
  669 
  670 /*
  671  * fasync_helper() is used by almost all character device drivers
  672  * to set up the fasync queue, and for regular files by the file
  673  * lease code. It returns negative on error, 0 if it did no changes
  674  * and positive if it added/deleted the entry.
  675  */
  676 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
  677 {
  678         if (!on)
  679                 return fasync_remove_entry(filp, fapp);
  680         return fasync_add_entry(fd, filp, fapp);
  681 }
  682 
  683 EXPORT_SYMBOL(fasync_helper);
  684 
  685 /*
  686  * rcu_read_lock() is held
  687  */
  688 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
  689 {
  690         while (fa) {
  691                 struct fown_struct *fown;
  692                 unsigned long flags;
  693 
  694                 if (fa->magic != FASYNC_MAGIC) {
  695                         printk(KERN_ERR "kill_fasync: bad magic number in "
  696                                "fasync_struct!\n");
  697                         return;
  698                 }
  699                 spin_lock_irqsave(&fa->fa_lock, flags);
  700                 if (fa->fa_file) {
  701                         fown = &fa->fa_file->f_owner;
  702                         /* Don't send SIGURG to processes which have not set a
  703                            queued signum: SIGURG has its own default signalling
  704                            mechanism. */
  705                         if (!(sig == SIGURG && fown->signum == 0))
  706                                 send_sigio(fown, fa->fa_fd, band);
  707                 }
  708                 spin_unlock_irqrestore(&fa->fa_lock, flags);
  709                 fa = rcu_dereference(fa->fa_next);
  710         }
  711 }
  712 
  713 void kill_fasync(struct fasync_struct **fp, int sig, int band)
  714 {
  715         /* First a quick test without locking: usually
  716          * the list is empty.
  717          */
  718         if (*fp) {
  719                 rcu_read_lock();
  720                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
  721                 rcu_read_unlock();
  722         }
  723 }
  724 EXPORT_SYMBOL(kill_fasync);
  725 
  726 static int __init fcntl_init(void)
  727 {
  728         /*
  729          * Please add new bits here to ensure allocation uniqueness.
  730          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
  731          * is defined as O_NONBLOCK on some platforms and not on others.
  732          */
  733         BUILD_BUG_ON(19 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
  734                 O_RDONLY        | O_WRONLY      | O_RDWR        |
  735                 O_CREAT         | O_EXCL        | O_NOCTTY      |
  736                 O_TRUNC         | O_APPEND      | /* O_NONBLOCK | */
  737                 __O_SYNC        | O_DSYNC       | FASYNC        |
  738                 O_DIRECT        | O_LARGEFILE   | O_DIRECTORY   |
  739                 O_NOFOLLOW      | O_NOATIME     | O_CLOEXEC     |
  740                 __FMODE_EXEC    | O_PATH
  741                 ));
  742 
  743         fasync_cache = kmem_cache_create("fasync_cache",
  744                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
  745         return 0;
  746 }
  747 
  748 module_init(fcntl_init)
Cache object: 6ed91d9f7be2dc3197e5779524687b49
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FreeBSD/Linux Kernel Cross Reference sys/fs/fcntl.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/fcntl.c
