cregit-Linux how code gets into the kernel

Release 4.15 fs/file.c

Directory: fs
// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/file.c
 *
 *  Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
 *
 *  Manage the dynamic fd arrays in the process files_struct.
 */

#include <linux/syscalls.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/time.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>


unsigned int sysctl_nr_open __read_mostly = 1024*1024;

unsigned int sysctl_nr_open_min = BITS_PER_LONG;
/* our min() is unusable in constant expressions ;-/ */

#define __const_min(x, y) ((x) < (y) ? (x) : (y))

unsigned int sysctl_nr_open_max =
	__const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG;


static void __free_fdtable(struct fdtable *fdt) { kvfree(fdt->fd); kvfree(fdt->open_fds); kfree(fdt); }

Contributors

PersonTokensPropCommitsCommitProp
Dipankar Sarma1240.00%225.00%
Linus Torvalds (pre-git)723.33%112.50%
Changli Gao620.00%112.50%
Al Viro26.67%112.50%
Linus Torvalds13.33%112.50%
Vadim Lobanov13.33%112.50%
Prasanna Meda13.33%112.50%
Total30100.00%8100.00%


static void free_fdtable_rcu(struct rcu_head *rcu) { __free_fdtable(container_of(rcu, struct fdtable, rcu)); }

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Dipankar Sarma2187.50%133.33%
Al Viro312.50%266.67%
Total24100.00%3100.00%

#define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr)) #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long)) /* * Copy 'count' fd bits from the old table to the new table and clear the extra * space if any. This does not copy the file pointers. Called with the files * spinlock held for write. */
static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt, unsigned int count) { unsigned int cpy, set; cpy = count / BITS_PER_BYTE; set = (nfdt->max_fds - count) / BITS_PER_BYTE; memcpy(nfdt->open_fds, ofdt->open_fds, cpy); memset((char *)nfdt->open_fds + cpy, 0, set); memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); memset((char *)nfdt->close_on_exec + cpy, 0, set); cpy = BITBIT_SIZE(count); set = BITBIT_SIZE(nfdt->max_fds) - cpy; memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy); memset((char *)nfdt->full_fds_bits + cpy, 0, set); }

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PersonTokensPropCommitsCommitProp
Dipankar Sarma4831.58%120.00%
Vadim Lobanov4529.61%240.00%
Eric Biggers3925.66%120.00%
Linus Torvalds (pre-git)2013.16%120.00%
Total152100.00%5100.00%

/* * Copy all file descriptors from the old table to the new, expanded table and * clear the extra space. Called with the files spinlock held for write. */
static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) { unsigned int cpy, set; BUG_ON(nfdt->max_fds < ofdt->max_fds); cpy = ofdt->max_fds * sizeof(struct file *); set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *); memcpy(nfdt->fd, ofdt->fd, cpy); memset((char *)nfdt->fd + cpy, 0, set); copy_fd_bitmaps(nfdt, ofdt, ofdt->max_fds); }

Contributors

PersonTokensPropCommitsCommitProp
Eric Biggers6662.26%133.33%
Linus Torvalds3936.79%133.33%
Linus Torvalds (pre-git)10.94%133.33%
Total106100.00%3100.00%


static struct fdtable * alloc_fdtable(unsigned int nr) { struct fdtable *fdt; void *data; /* * Figure out how many fds we actually want to support in this fdtable. * Allocation steps are keyed to the size of the fdarray, since it * grows far faster than any of the other dynamic data. We try to fit * the fdarray into comfortable page-tuned chunks: starting at 1024B * and growing in powers of two from there on. */ nr /= (1024 / sizeof(struct file *)); nr = roundup_pow_of_two(nr + 1); nr *= (1024 / sizeof(struct file *)); /* * Note that this can drive nr *below* what we had passed if sysctl_nr_open * had been set lower between the check in expand_files() and here. Deal * with that in caller, it's cheaper that way. * * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise * bitmaps handling below becomes unpleasant, to put it mildly... */ if (unlikely(nr > sysctl_nr_open)) nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1; fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL_ACCOUNT); if (!fdt) goto out; fdt->max_fds = nr; data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT); if (!data) goto out_fdt; fdt->fd = data; data = kvmalloc(max_t(size_t, 2 * nr / BITS_PER_BYTE + BITBIT_SIZE(nr), L1_CACHE_BYTES), GFP_KERNEL_ACCOUNT); if (!data) goto out_arr; fdt->open_fds = data; data += nr / BITS_PER_BYTE; fdt->close_on_exec = data; data += nr / BITS_PER_BYTE; fdt->full_fds_bits = data; return fdt; out_arr: kvfree(fdt->fd); out_fdt: kfree(fdt); out: return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
Vadim Lobanov10646.29%214.29%
Dipankar Sarma4519.65%214.29%
Linus Torvalds (pre-git)229.61%17.14%
Al Viro198.30%214.29%
Linus Torvalds177.42%17.14%
David Howells73.06%17.14%
Michal Hocko73.06%17.14%
Eric Dumazet20.87%17.14%
Changli Gao20.87%17.14%
Vladimir Davydov10.44%17.14%
Prasanna Meda10.44%17.14%
Total229100.00%14100.00%

/* * Expand the file descriptor table. * This function will allocate a new fdtable and both fd array and fdset, of * the given size. * Return <0 error code on error; 1 on successful completion. * The files->file_lock should be held on entry, and will be held on exit. */
static int expand_fdtable(struct files_struct *files, unsigned int nr) __releases(files->file_lock) __acquires(files->file_lock) { struct fdtable *new_fdt, *cur_fdt; spin_unlock(&files->file_lock); new_fdt = alloc_fdtable(nr); /* make sure all __fd_install() have seen resize_in_progress * or have finished their rcu_read_lock_sched() section. */ if (atomic_read(&files->count) > 1) synchronize_sched(); spin_lock(&files->file_lock); if (!new_fdt) return -ENOMEM; /* * extremely unlikely race - sysctl_nr_open decreased between the check in * caller and alloc_fdtable(). Cheaper to catch it here... */ if (unlikely(new_fdt->max_fds <= nr)) { __free_fdtable(new_fdt); return -EMFILE; } cur_fdt = files_fdtable(files); BUG_ON(nr < cur_fdt->max_fds); copy_fdtable(new_fdt, cur_fdt); rcu_assign_pointer(files->fdt, new_fdt); if (cur_fdt != &files->fdtab) call_rcu(&cur_fdt->rcu, free_fdtable_rcu); /* coupled with smp_rmb() in __fd_install() */ smp_wmb(); return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Dipankar Sarma5131.10%110.00%
Vadim Lobanov3521.34%220.00%
Al Viro3219.51%330.00%
Eric Dumazet2414.63%110.00%
Linus Torvalds (pre-git)2012.20%110.00%
Changli Gao10.61%110.00%
Alexey Dobriyan10.61%110.00%
Total164100.00%10100.00%

/* * Expand files. * This function will expand the file structures, if the requested size exceeds * the current capacity and there is room for expansion. * Return <0 error code on error; 0 when nothing done; 1 when files were * expanded and execution may have blocked. * The files->file_lock should be held on entry, and will be held on exit. */
static int expand_files(struct files_struct *files, unsigned int nr) __releases(files->file_lock) __acquires(files->file_lock) { struct fdtable *fdt; int expanded = 0; repeat: fdt = files_fdtable(files); /* Do we need to expand? */ if (nr < fdt->max_fds) return expanded; /* Can we expand? */ if (nr >= sysctl_nr_open) return -EMFILE; if (unlikely(files->resize_in_progress)) { spin_unlock(&files->file_lock); expanded = 1; wait_event(files->resize_wait, !files->resize_in_progress); spin_lock(&files->file_lock); goto repeat; } /* All good, so we try */ files->resize_in_progress = true; expanded = expand_fdtable(files, nr); files->resize_in_progress = false; wake_up_all(&files->resize_wait); return expanded; }

Contributors

PersonTokensPropCommitsCommitProp
Eric Dumazet9262.16%225.00%
Prasanna Meda2718.24%112.50%
Dipankar Sarma1912.84%225.00%
Vadim Lobanov85.41%112.50%
Al Viro10.68%112.50%
Alexey Dobriyan10.68%112.50%
Total148100.00%8100.00%


static inline void __set_close_on_exec(unsigned int fd, struct fdtable *fdt) { __set_bit(fd, fdt->close_on_exec); }

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Al Viro2496.00%150.00%
Alexey Dobriyan14.00%150.00%
Total25100.00%2100.00%


static inline void __clear_close_on_exec(unsigned int fd, struct fdtable *fdt) { if (test_bit(fd, fdt->close_on_exec)) __clear_bit(fd, fdt->close_on_exec); }

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PersonTokensPropCommitsCommitProp
Al Viro2466.67%133.33%
Linus Torvalds1130.56%133.33%
Alexey Dobriyan12.78%133.33%
Total36100.00%3100.00%


static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt) { __set_bit(fd, fdt->open_fds); fd /= BITS_PER_LONG; if (!~fdt->open_fds[fd]) __set_bit(fd, fdt->full_fds_bits); }

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PersonTokensPropCommitsCommitProp
Linus Torvalds2551.02%150.00%
Al Viro2448.98%150.00%
Total49100.00%2100.00%


static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt) { __clear_bit(fd, fdt->open_fds); __clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits); }

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Al Viro2466.67%150.00%
Linus Torvalds1233.33%150.00%
Total36100.00%2100.00%


static unsigned int count_open_files(struct fdtable *fdt) { unsigned int size = fdt->max_fds; unsigned int i; /* Find the last open fd */ for (i = size / BITS_PER_LONG; i > 0; ) { if (fdt->open_fds[--i]) break; } i = (i + 1) * BITS_PER_LONG; return i; }

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PersonTokensPropCommitsCommitProp
Al Viro5992.19%133.33%
Alexey Dobriyan34.69%133.33%
David Howells23.12%133.33%
Total64100.00%3100.00%

/* * Allocate a new files structure and copy contents from the * passed in files structure. * errorp will be valid only when the returned files_struct is NULL. */
struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) { struct files_struct *newf; struct file **old_fds, **new_fds; unsigned int open_files, i; struct fdtable *old_fdt, *new_fdt; *errorp = -ENOMEM; newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); if (!newf) goto out; atomic_set(&newf->count, 1); spin_lock_init(&newf->file_lock); newf->resize_in_progress = false; init_waitqueue_head(&newf->resize_wait); newf->next_fd = 0; new_fdt = &newf->fdtab; new_fdt->max_fds = NR_OPEN_DEFAULT; new_fdt->close_on_exec = newf->close_on_exec_init; new_fdt->open_fds = newf->open_fds_init; new_fdt->full_fds_bits = newf->full_fds_bits_init; new_fdt->fd = &newf->fd_array[0]; spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); open_files = count_open_files(old_fdt); /* * Check whether we need to allocate a larger fd array and fd set. */ while (unlikely(open_files > new_fdt->max_fds)) { spin_unlock(&oldf->file_lock); if (new_fdt != &newf->fdtab) __free_fdtable(new_fdt); new_fdt = alloc_fdtable(open_files - 1); if (!new_fdt) { *errorp = -ENOMEM; goto out_release; } /* beyond sysctl_nr_open; nothing to do */ if (unlikely(new_fdt->max_fds < open_files)) { __free_fdtable(new_fdt); *errorp = -EMFILE; goto out_release; } /* * Reacquire the oldf lock and a pointer to its fd table * who knows it may have a new bigger fd table. We need * the latest pointer. */ spin_lock(&oldf->file_lock); old_fdt = files_fdtable(oldf); open_files = count_open_files(old_fdt); } copy_fd_bitmaps(new_fdt, old_fdt, open_files); old_fds = old_fdt->fd; new_fds = new_fdt->fd; for (i = open_files; i != 0; i--) { struct file *f = *old_fds++; if (f) { get_file(f); } else { /* * The fd may be claimed in the fd bitmap but not yet * instantiated in the files array if a sibling thread * is partway through open(). So make sure that this * fd is available to the new process. */ __clear_open_fd(open_files - i, new_fdt); } rcu_assign_pointer(*new_fds++, f); } spin_unlock(&oldf->file_lock); /* clear the remainder */ memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *)); rcu_assign_pointer(newf->fdt, new_fdt); return newf; out_release: kmem_cache_free(files_cachep, newf); out: return NULL; }

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PersonTokensPropCommitsCommitProp
Al Viro38290.09%440.00%
Eric Dumazet143.30%110.00%
Eric Biggers133.07%110.00%
Linus Torvalds112.59%110.00%
Changli Gao20.47%110.00%
Alexey Dobriyan10.24%110.00%
David Howells10.24%110.00%
Total424100.00%10100.00%


static struct fdtable *close_files(struct files_struct * files) { /* * It is safe to dereference the fd table without RCU or * ->file_lock because this is the last reference to the * files structure. */ struct fdtable *fdt = rcu_dereference_raw(files->fdt); unsigned int i, j = 0; for (;;) { unsigned long set; i = j * BITS_PER_LONG; if (i >= fdt->max_fds) break; set = fdt->open_fds[j++]; while (set) { if (set & 1) { struct file * file = xchg(&fdt->fd[i], NULL); if (file) { filp_close(file, files); cond_resched_rcu_qs(); } } i++; set >>= 1; } } return fdt; }

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PersonTokensPropCommitsCommitProp
Al Viro10783.59%125.00%
Oleg Nesterov1914.84%125.00%
Paul E. McKenney10.78%125.00%
Alexey Dobriyan10.78%125.00%
Total128100.00%4100.00%


struct files_struct *get_files_struct(struct task_struct *task) { struct files_struct *files; task_lock(task); files = task->files; if (files) atomic_inc(&files->count); task_unlock(task); return files; }

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Al Viro48100.00%1100.00%
Total48100.00%1100.00%


void put_files_struct(struct files_struct *files) { if (atomic_dec_and_test(&files->count)) { struct fdtable *fdt = close_files(files); /* free the arrays if they are not embedded */ if (fdt != &files->fdtab) __free_fdtable(fdt); kmem_cache_free(files_cachep, files); } }

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Al Viro4888.89%266.67%
Oleg Nesterov611.11%133.33%
Total54100.00%3100.00%


void reset_files_struct(struct files_struct *files) { struct task_struct *tsk = current; struct files_struct *old; old = tsk->files; task_lock(tsk); tsk->files = files; task_unlock(tsk); put_files_struct(old); }

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Al Viro49100.00%1100.00%
Total49100.00%1100.00%


void exit_files(struct task_struct *tsk) { struct files_struct * files = tsk->files; if (files) { task_lock(tsk); tsk->files = NULL; task_unlock(tsk); put_files_struct(files); } }

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Al Viro46100.00%1100.00%
Total46100.00%1100.00%

struct files_struct init_files = { .count = ATOMIC_INIT(1), .fdt = &init_files.fdtab, .fdtab = { .max_fds = NR_OPEN_DEFAULT, .fd = &init_files.fd_array[0], .close_on_exec = init_files.close_on_exec_init, .open_fds = init_files.open_fds_init, .full_fds_bits = init_files.full_fds_bits_init, }, .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock), };
static unsigned int find_next_fd(struct fdtable *fdt, unsigned int start) { unsigned int maxfd = fdt->max_fds; unsigned int maxbit = maxfd / BITS_PER_LONG; unsigned int bitbit = start / BITS_PER_LONG; bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG; if (bitbit > maxfd) return maxfd; if (bitbit > start) start = bitbit; return find_next_zero_bit(fdt->open_fds, maxfd, start); }

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Linus Torvalds8194.19%150.00%
Alexey Dobriyan55.81%150.00%
Total86100.00%2100.00%

/* * allocate a file descriptor, mark it busy. */
int __alloc_fd(struct files_struct *files, unsigned start, unsigned end, unsigned flags) { unsigned int fd; int error; struct fdtable *fdt; spin_lock(&files->file_lock); repeat: fdt = files_fdtable(files); fd = start; if (fd < files->next_fd) fd = files->next_fd; if (fd < fdt->max_fds) fd = find_next_fd(fdt, fd); /* * N.B. For clone tasks sharing a files structure, this test * will limit the total number of files that can be opened. */ error = -EMFILE; if (fd >= end) goto out; error = expand_files(files, fd); if (error < 0) goto out; /* * If we needed to expand the fs array we * might have blocked - try again. */ if (error) goto repeat; if (start <= files->next_fd) files->next_fd = fd + 1; __set_open_fd(fd, fdt); if (flags & O_CLOEXEC) __set_close_on_exec(fd, fdt); else __clear_close_on_exec(fd, fdt); error = fd; #if 1 /* Sanity check */ if (rcu_access_pointer(fdt->fd[fd]) != NULL) { printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); rcu_assign_pointer(fdt->fd[fd], NULL); } #endif out: spin_unlock(&files->file_lock); return error; }

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PersonTokensPropCommitsCommitProp
Al Viro22297.80%350.00%
David Howells31.32%116.67%
Linus Torvalds10.44%116.67%
Paul E. McKenney10.44%116.67%
Total227100.00%6100.00%


static int alloc_fd(unsigned start, unsigned flags) { return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags); }

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Al Viro29100.00%2100.00%
Total29100.00%2100.00%


int get_unused_fd_flags(unsigned flags) { return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags); }

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Al Viro25100.00%3100.00%
Total25100.00%3100.00%

EXPORT_SYMBOL(get_unused_fd_flags);
static void __put_unused_fd(struct files_struct *files, unsigned int fd) { struct fdtable *fdt = files_fdtable(files); __clear_open_fd(fd, fdt); if (fd < files->next_fd) files->next_fd = fd; }

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Al Viro46100.00%1100.00%
Total46100.00%1100.00%


void put_unused_fd(unsigned int fd) { struct files_struct *files = current->files; spin_lock(&files->file_lock); __put_unused_fd(files, fd); spin_unlock(&files->file_lock); }

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PersonTokensPropCommitsCommitProp
Al Viro41100.00%1100.00%
Total41100.00%1100.00%

EXPORT_SYMBOL(put_unused_fd); /* * Install a file pointer in the fd array. * * The VFS is full of places where we drop the files lock between * setting the open_fds bitmap and installing the file in the file * array. At any such point, we are vulnerable to a dup2() race * installing a file in the array before us. We need to detect this and * fput() the struct file we are about to overwrite in this case. * * It should never happen - if we allow dup2() do it, _really_ bad things * will follow. * * NOTE: __fd_install() variant is really, really low-level; don't * use it unless you are forced to by truly lousy API shoved down * your throat. 'files' *MUST* be either current->files or obtained * by get_files_struct(current) done by whoever had given it to you, * or really bad things will happen. Normally you want to use * fd_install() instead. */
void __fd_install(struct files_struct *files, unsigned int fd, struct file *file) { struct fdtable *fdt; rcu_read_lock_sched(); if (unlikely(files->resize_in_progress)) { rcu_read_unlock_sched(); spin_lock(&files->file_lock); fdt = files_fdtable(files); BUG_ON(fdt->fd[fd] != NULL); rcu_assign_pointer(fdt->fd[fd], file); spin_unlock(&files->file_lock); return; } /* coupled with smp_wmb() in expand_fdtable() */ smp_rmb(); fdt = rcu_dereference_sched(files->fdt); BUG_ON(fdt->fd[fd] != NULL); rcu_assign_pointer(fdt->fd[fd], file); rcu_read_unlock_sched(); }

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PersonTokensPropCommitsCommitProp
Al Viro6046.51%250.00%
Mateusz Guzik4131.78%125.00%
Eric Dumazet2821.71%125.00%
Total129100.00%4100.00%


void fd_install(unsigned int fd, struct file *file) { __fd_install(current->files, fd, file); }

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Al Viro25100.00%1100.00%
Total25100.00%1100.00%

EXPORT_SYMBOL(fd_install); /* * The same warnings as for __alloc_fd()/__fd_install() apply here... */
int __close_fd(struct files_struct *files, unsigned fd) { struct file *file; struct fdtable *fdt; spin_lock(&files->file_lock); fdt = files_fdtable(files); if (fd >= fdt->max_fds) goto out_unlock; file = fdt->fd[fd]; if (!file) goto out_unlock; rcu_assign_pointer(fdt->fd[fd], NULL); __put_unused_fd(files, fd); spin_unlock(&files->file_lock); return filp_close(file, files); out_unlock: spin_unlock(&files->file_lock); return -EBADF; }

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PersonTokensPropCommitsCommitProp
Al Viro115100.00%1100.00%
Total115100.00%1100.00%


void do_close_on_exec(struct files_struct *files) { unsigned i; struct fdtable *fdt; /* exec unshares first */ spin_lock(&files->file_lock); for (i = 0; ; i++) { unsigned long set; unsigned fd = i * BITS_PER_LONG; fdt = files_fdtable(files); if (fd >= fdt->max_fds) break; set = fdt->close_on_exec[i]; if (!set) continue; fdt->close_on_exec[i] = 0; for ( ; set ; fd++, set >>= 1) { struct file *file; if (!(set & 1)) continue; file = fdt->fd[fd]; if (!file) continue; rcu_assign_pointer(fdt->fd[fd], NULL); __put_unused_fd(files, fd); spin_unlock(&files->file_lock); filp_close(file, files); cond_resched(); spin_lock(&files->file_lock); } } spin_unlock(&files->file_lock); }

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PersonTokensPropCommitsCommitProp
Al Viro187100.00%1100.00%
Total187100.00%1100.00%


static struct file *__fget(unsigned int fd, fmode_t mask) { struct files_struct *files = current->files; struct file *file; rcu_read_lock(); loop: file = fcheck_files(files, fd); if (file) { /* File object ref couldn't be taken. * dup2() atomicity guarantee is the reason * we loop to catch the new file (or NULL pointer) */ if (file->f_mode & mask) file = NULL; else if (!get_file_rcu(file)) goto loop; } rcu_read_unlock(); return file; }

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Al Viro5467.50%125.00%
Eric Dumazet1417.50%125.00%
Oleg Nesterov1113.75%125.00%
Konstantin Khlebnikov11.25%125.00%
Total80100.00%4100.00%


struct file *fget(unsigned int fd) { return __fget(fd, FMODE_PATH); }

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Oleg Nesterov19100.00%1100.00%
Total19100.00%1100.00%

EXPORT_SYMBOL(fget);
struct file *fget_raw(unsigned int fd) { return __fget(fd, 0); }

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Al Viro1578.95%150.00%
Oleg Nesterov421.05%150.00%
Total19100.00%2100.00%

EXPORT_SYMBOL(fget_raw); /* * Lightweight file lookup - no refcnt increment if fd table isn't shared. * * You can use this instead of fget if you satisfy all of the following * conditions: * 1) You must call fput_light before exiting the syscall and returning control * to userspace (i.e. you cannot remember the returned struct file * after * returning to userspace). * 2) You must not call filp_close on the returned struct file * in between * calls to fget_light and fput_light. * 3) You must not clone the current task in between the calls to fget_light * and fput_light. * * The fput_needed flag returned by fget_light should be passed to the * corresponding fput_light. */
static unsigned long __fget_light(unsigned int fd, fmode_t mask) { struct files_struct *files = current->files; struct file *file; if (atomic_read(&files->count) == 1) { file = __fcheck_files(files, fd); if (!file || unlikely(file->f_mode & mask)) return 0; return (unsigned long)file; } else { file = __fget(fd, mask); if (!file) return 0; return FDPUT_FPUT | (unsigned long)file; } }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro9187.50%240.00%
Oleg Nesterov1312.50%360.00%
Total104100.00%5100.00%


unsigned long __fdget(unsigned int fd) { return __fget_light(fd, FMODE_PATH); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov1583.33%150.00%
Al Viro316.67%150.00%
Total18100.00%2100.00%

EXPORT_SYMBOL(__fdget);
unsigned long __fdget_raw(unsigned int fd) { return __fget_light(fd, 0); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro1583.33%266.67%
Oleg Nesterov316.67%133.33%
Total18100.00%3100.00%


unsigned long __fdget_pos(unsigned int fd) { unsigned long v = __fdget(fd); struct file *file = (struct file *)(v & ~3); if (file && (file->f_mode & FMODE_ATOMIC_POS)) { if (file_count(file) > 1) { v |= FDPUT_POS_UNLOCK; mutex_lock(&file->f_pos_lock); } } return v; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro5471.05%250.00%
Eric Biggers2127.63%125.00%
Oleg Nesterov11.32%125.00%
Total76100.00%4100.00%


void __f_unlock_pos(struct file *f) { mutex_unlock(&f->f_pos_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro18100.00%1100.00%
Total18100.00%1100.00%

/* * We only lock f_pos if we have threads or if the file might be * shared with another process. In both cases we'll have an elevated * file count (done either by fdget() or by fork()). */
void set_close_on_exec(unsigned int fd, int flag) { struct files_struct *files = current->files; struct fdtable *fdt; spin_lock(&files->file_lock); fdt = files_fdtable(files); if (flag) __set_close_on_exec(fd, fdt); else __clear_close_on_exec(fd, fdt); spin_unlock(&files->file_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro68100.00%1100.00%
Total68100.00%1100.00%


bool get_close_on_exec(unsigned int fd) { struct files_struct *files = current->files; struct fdtable *fdt; bool res; rcu_read_lock(); fdt = files_fdtable(files); res = close_on_exec(fd, fdt); rcu_read_unlock(); return res; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro51100.00%1100.00%
Total51100.00%1100.00%


static int do_dup2(struct files_struct *files, struct file *file, unsigned fd, unsigned flags) __releases(&files->file_lock

Contributors

PersonTokensPropCommitsCommitProp
Al Viro23100.00%2100.00%
Total23100.00%2100.00%

) { struct file *tofree; struct fdtable *fdt; /* * We need to detect attempts to do dup2() over allocated but still * not finished descriptor. NB: OpenBSD avoids that at the price of * extra work in their equivalent of fget() - they insert struct * file immediately after grabbing descriptor, mark it larval if * more work (e.g. actual opening) is needed and make sure that * fget() treats larval files as absent. Potentially interesting, * but while extra work in fget() is trivial, locking implications * and amount of surgery on open()-related paths in VFS are not. * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" * deadlocks in rather amusing ways, AFAICS. All of that is out of * scope of POSIX or SUS, since neither considers shared descriptor * tables and this condition does not arise without those. */ fdt = files_fdtable(files); tofree = fdt->fd[fd]; if (!tofree && fd_is_open(fd, fdt)) goto Ebusy; get_file(file); rcu_assign_pointer(fdt->fd[fd], file); __set_open_fd(fd, fdt); if (flags & O_CLOEXEC) __set_close_on_exec(fd, fdt); else __clear_close_on_exec(fd, fdt); spin_unlock(&files->file_lock); if (tofree) filp_close(tofree, files); return fd; Ebusy: spin_unlock(&files->file_lock); return -EBUSY; }
int replace_fd(unsigned fd, struct file *file, unsigned flags) { int err; struct files_struct *files = current->files; if (!file) return __close_fd(files, fd); if (fd >= rlimit(RLIMIT_NOFILE)) return -EBADF; spin_lock(&files->file_lock); err = expand_files(files, fd); if (unlikely(err < 0)) goto out_unlock; return do_dup2(files, file, fd, flags); out_unlock: spin_unlock(&files->file_lock); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro108100.00%2100.00%
Total108100.00%2100.00%

SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags) { int err = -EBADF; struct file *file; struct files_struct *files = current->files; if ((flags & ~O_CLOEXEC) != 0) return -EINVAL; if (unlikely(oldfd == newfd)) return -EINVAL; if (newfd >= rlimit(RLIMIT_NOFILE)) return -EBADF; spin_lock(&files->file_lock); err = expand_files(files, newfd); file = fcheck(oldfd); if (unlikely(!file)) goto Ebadf; if (unlikely(err < 0)) { if (err == -EMFILE) goto Ebadf; goto out_unlock; } return do_dup2(files, file, newfd, flags); Ebadf: err = -EBADF; out_unlock: spin_unlock(&files->file_lock); return err; } SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) { if (unlikely(newfd == oldfd)) { /* corner case */ struct files_struct *files = current->files; int retval = oldfd; rcu_read_lock(); if (!fcheck_files(files, oldfd)) retval = -EBADF; rcu_read_unlock(); return retval; } return sys_dup3(oldfd, newfd, 0); } SYSCALL_DEFINE1(dup, unsigned int, fildes) { int ret = -EBADF; struct file *file = fget_raw(fildes); if (file) { ret = get_unused_fd_flags(0); if (ret >= 0) fd_install(ret, file); else fput(file); } return ret; }
int f_dupfd(unsigned int from, struct file *file, unsigned flags) { int err; if (from >= rlimit(RLIMIT_NOFILE)) return -EINVAL; err = alloc_fd(from, flags); if (err >= 0) { get_file(file); fd_install(err, file); } return err; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro65100.00%1100.00%
Total65100.00%1100.00%


int iterate_fd(struct files_struct *files, unsigned n, int (*f)(const void *, struct file *, unsigned), const void *p) { struct fdtable *fdt; int res = 0; if (!files) return 0; spin_lock(&files->file_lock); for (fdt = files_fdtable(files); n < fdt->max_fds; n++) { struct file *file; file = rcu_dereference_check_fdtable(files, fdt->fd[n]); if (!file) continue; res = f(p, file, n); if (res) break; } spin_unlock(&files->file_lock); return res; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro133100.00%2100.00%
Total133100.00%2100.00%

EXPORT_SYMBOL(iterate_fd);

Overall Contributors

PersonTokensPropCommitsCommitProp
Al Viro290469.39%3442.50%
Linus Torvalds2235.33%56.25%
Dipankar Sarma2084.97%33.75%
Vadim Lobanov1974.71%45.00%
Eric Dumazet1824.35%33.75%
Eric Biggers1413.37%22.50%
Oleg Nesterov912.17%56.25%
Linus Torvalds (pre-git)852.03%11.25%
Mateusz Guzik410.98%11.25%
Prasanna Meda290.69%11.25%
Alexey Dobriyan190.45%22.50%
David Howells130.31%22.50%
Richard W.M. Jones130.31%11.25%
Changli Gao110.26%11.25%
Michal Hocko70.17%11.25%
Yann Droneaud40.10%11.25%
Rasmus Villemoes30.07%11.25%
Andrew Morton30.07%11.25%
Paul E. McKenney20.05%22.50%
Dave Jones10.02%11.25%
Greg Kroah-Hartman10.02%11.25%
Adrian Bunk10.02%11.25%
Ingo Molnar10.02%11.25%
Paul Gortmaker10.02%11.25%
Konstantin Khlebnikov10.02%11.25%
Rusty Russell10.02%11.25%
Vladimir Davydov10.02%11.25%
Thomas Gleixner10.02%11.25%
Total4185100.00%80100.00%
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