2017年02月09日 情報科学類 オペレーティングシステム II 筑波大学 システム情報系 新城 靖 <yas@cs.tsukuba.ac.jp>
このページは、次の URL にあります。
http://www.coins.tsukuba.ac.jp/~yas/coins/os2-2016/2017-02-09
あるいは、次のページから手繰っていくこともできます。
http://www.coins.tsukuba.ac.jp/~yas/
http://www.cs.tsukuba.ac.jp/~yas/
試験について
図? 割り込み処理の前半部分と後半部分
割り込みハンドラ(前半部)と後半部の役割分担の目安。
注意1: Tasklet は、task 構造体とはまったく関係ない。名前がよくない。
注意2: Softirq という用語を、割り込み処理の後半部という意味で使う人もい る。
注意3: 伝統的なUnixでは、top half は、システム・コールから派生する上位 層の処理、bottom half は、割り込みから派生する下位層の処理の意味で使わ れることがある。Linux では、top half, bottom half は、割り込み処理の前 半部分と後半部分の意味に使う。
Tasklet で1つの仕事は次のような、struct tasklet_struct で表現される。
linux-4.9.1/include/linux/interrupt.h 514: struct tasklet_struct 515: { 516: struct tasklet_struct *next; 517: unsigned long state; 518: atomic_t count; 519: void (*func)(unsigned long); 520: unsigned long data; 521: };
図? Taskletにおける仕事のキュー
DECLARE_TASKLET(name, func, data) 有効な(count==0) の struct tasklet_struct を宣言する DECLARE_TASKLET_DISABLED(name, func, data) 無効な(count==1) の struct tasklet_struct を宣言する
void tasklet_init(struct tasklet_struct *t, void (*func)(unsigned long), unsigned long data);その他に、生成消滅有効無効に関して次のような操作がある。
void tasklet_handler(unsigned long data) { ... }
void tasklet_schedule(struct tasklet_struct *t) Tasklet t を通常の優先度でスケジュールする void tasklet_hi_schedule(struct tasklet_struct *t) Tasklet t を高優先度でスケジュールするすると、それは「そのうちに」1度だけ実行される。
linux-4.9.1/drivers/net/wireless/ath/ath9k/ath9k.h 955: struct ath_softc { ... 962: struct tasklet_struct intr_tq; 963: struct tasklet_struct bcon_tasklet; ... 1049: }; linux-4.9.1/drivers/net/wireless/ath/ath9k/init.c 558: static int ath9k_init_softc(u16 devid, struct ath_softc *sc, 559: const struct ath_bus_ops *bus_ops) 560: { ... 633: tasklet_init(&sc->intr_tq, ath9k_tasklet, (unsigned long)sc); 634: tasklet_init(&sc->bcon_tasklet, ath9k_beacon_tasklet, 635: (unsigned long)sc); ... 692: }
linux-4.9.1/drivers/net/wireless/ath/ath9k/main.c 486: irqreturn_t ath_isr(int irq, void *dev) 487: { ... 504: struct ath_softc *sc = dev; ... 507: enum ath9k_int status; ... 509: bool sched = false; ... 529: ath9k_hw_getisr(ah, &status, &sync_cause); /* NB: clears ISR too */ ... 546: if (status & SCHED_INTR) 547: sched = true; ... 560: if (status & ATH9K_INT_SWBA) 561: tasklet_schedule(&sc->bcon_tasklet); ... 588: if (sched) { 589: /* turn off every interrupt */ 590: ath9k_hw_disable_interrupts(ah); 591: tasklet_schedule(&sc->intr_tq); 592: } ... 594: return IRQ_HANDLED; ... 597: } 369: void ath9k_tasklet(unsigned long data) 370: { ... 484: } linux-4.9.1/drivers/net/wireless/ath/ath9k/main.c 388: void ath9k_beacon_tasklet(unsigned long data) 389: { ... 508: }
図? Work Queueにおける仕事のキュー
キューにつながれる仕事は、Tasklet の仕事とほとんど同じで、関数へのポイ ンタ func と data からなる。処理の主体が、ワーカ・スレッドと呼ばれるカー ネル・レベルのスレッドである所が違う。
$ ps alx|egrep events
1 0 19 2 20 0 0 0 worker S ? 0:12 [events/0]
1 0 20 2 20 0 0 0 worker S ? 0:08 [events/1]
1 0 21 2 20 0 0 0 worker S ? 0:08 [events/2]
1 0 22 2 20 0 0 0 worker S ? 0:10 [events/3]
0 1013 3242 2450 20 0 105236 900 pipe_w S+ pts/3 0:00 egrep events
$
汎用の Work Queue のワーカ・スレッドの他に、専用のワーカ・スレッドを作
ることもできる。
linux-4.9.1/include/linux/workqueue.h 19: typedef void (*work_func_t)(struct work_struct *work); 100: struct work_struct { 101: atomic_long_t data; 102: struct list_head entry; 103: work_func_t func; ... 107: };
struct work_struct my_work; ... INIT_WORK(&my_work,my_work_handler);
void my_work_handler(struct work_struct *work) { ... }
schedule_work(&work);この結果、INIT_WORK() で設定したハンドラがワーカ・スレッドにより「その うち」に呼び出される。
schedule_work() では、即座に実行される可能性もある。少し後に実行したい (間を取りたい)時には、次の関数を呼ぶ。
schedule_delayed_work(&work,ticks);ticks は、どのくらい間をとるか。単位は、 ticks (jiffiesの単位)。 多くのシステムで10ミリ秒-1ミリ秒で、設定によって異なる。
解決策:
図? 層構造を用いたファイル・システムの実装
解決策
$ ls -l /usr/bin/{perl,perl5.10.1}
-rwxr-xr-x. 2 root root 13304 Nov 10 2015 /usr/bin/perl
-rwxr-xr-x. 2 root root 13304 Nov 10 2015 /usr/bin/perl5.10.1
$ ls -li /usr/bin/{perl,perl5.10.1}
1862030 -rwxr-xr-x. 2 root root 13304 Nov 10 2015 /usr/bin/perl
1862030 -rwxr-xr-x. 2 root root 13304 Nov 10 2015 /usr/bin/perl5.10.1
$
$ grep -v '#' /etc/fstab
UUID=9cfbc67e-781c-48d1-8303-1dde8ce87ee9 / ext4 defaults 1 1
UUID=bab1faf1-5f5b-4a2a-b24f-e850a2b0b82d /boot ext4 defaults 1 2
UUID=a1f61ff2-2c99-4c54-8c3e-2178eed3ec10 swap swap defaults 0 0
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
pentas-fs:/vol0/home /home nfs rw,hard,bg,nfsvers=3,intr 0 0
pentas-fs:/vol0/web /var/www nfs rw,hard,bg,nfsvers=3,intr 0 0
pentas-fs:/vol0/local3 /
$ df /
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda3 49071944 6721604 39857568 15% /
$ blkid /dev/sda3
/dev/sda3: UUID="9cfbc67e-781c-48d1-8303-1dde8ce87ee9" TYPE="ext4"
$ ls -l /dev/sda3
brw-rw----. 1 root disk 8, 3 Feb 2 10:50 /dev/sda3
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 50G 0 disk
|-sda1 8:1 0 512M 0 part /boot
|-sda2 8:2 0 2G 0 part [SWAP]
`-sda3 8:3 0 47.6G 0 part /
sr0 11:0 1 1024M 0 rom
$ ls -l /dev/sda
brw-rw----. 1 root disk 8, 0 Feb 2 10:50 /dev/sda
$
$ grep cd /etc/auto.misc
cd -fstype=iso9660,ro,nosuid,nodev :/dev/cdrom
$
STAT(2) Linux Programmer's Manual STAT(2) ... int stat(const char *path, struct stat *buf); ... struct stat { dev_t st_dev; /* ID of device containing file */ ino_t st_ino; /* inode number */ mode_t st_mode; /* protection */ nlink_t st_nlink; /* number of hard links */ uid_t st_uid; /* user ID of owner */ gid_t st_gid; /* group ID of owner */ dev_t st_rdev; /* device ID (if special file) */ off_t st_size; /* total size, in bytes */ blksize_t st_blksize; /* blocksize for filesystem I/O */ blkcnt_t st_blocks; /* number of blocks allocated */ time_t st_atime; /* time of last access */ time_t st_mtime; /* time of last modification */ time_t st_ctime; /* time of last status change */ };stat コマンドを使うと stat システム・コールで返される値に近いものが表示 される。
$ ls -l .bashrc
-rw-r--r--. 1 yas prof 241 Jun 19 2015 .bashrc
$ stat .bashrc
File: `.bashrc'
Size: 241 Blocks: 16 IO Block: 65536 regular file
Device: 13h/19d Inode: 29988667 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1013/ yas) Gid: ( 510/ prof)
Access: 2016-01-31 15:25:29.000000000 +0900
Modify: 2015-06-19 10:40:12.000860000 +0900
Change: 2016-01-30 16:39:59.001034000 +0900
$
図? スーパーブロック、inode、dentry、file
int fd1 = open("file1",O_RDONLY); int fd2 = open("file1",O_RDONLY);ファイル名 "file1" で表現されるファイルの inode 構造体は、1 個でも、 file 構造体は、2 個割り当てられる。
ディスク上には対応するデータ構造は存在しない。
linux-4.9.1/include/linux/fs.h 880: struct file { ... 885: struct path f_path; 886: struct inode *f_inode; /* cached value */ 887: const struct file_operations *f_op; ... 894: atomic_long_t f_count; ... 896: fmode_t f_mode; ... 898: loff_t f_pos; ... 908: void *private_data; ... 915: struct address_space *f_mapping; 916: } __attribute__((aligned(4))); /* lest something weird decides that 2 is OK */ linux-4.9.1/include/linux/path.h 7: struct path { 8: struct vfsmount *mnt; 9: struct dentry *dentry; 10: };
図? C言語によるオブジェクト指向の継承の実装方法。共通インスタンス変数・関数、固有インスタンス変数関数の置き方
struct fileの操作は、たとえば次のような形で行われる。 第1引数は、struct file *。
struct file *file; file->f_op->read(file, buf, count, pos);f_op には、次のような手続きがある。各ファイルシステム (ext4,nfs,tmpfs,...) ごとに、手続きの実体は異なるが、インタフェースは同じ。
linux-4.9.1/include/linux/fs.h 1696: struct file_operations { 1697: struct module *owner; 1698: loff_t (*llseek) (struct file *, loff_t, int); 1699: ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 1700: ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 1701: ssize_t (*read_iter) (struct kiocb *, struct iov_iter *); 1702: ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); 1703: int (*iterate) (struct file *, struct dir_context *); 1704: int (*iterate_shared) (struct file *, struct dir_context *); 1705: unsigned int (*poll) (struct file *, struct poll_table_struct *); 1706: long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); 1707: long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 1708: int (*mmap) (struct file *, struct vm_area_struct *); 1709: int (*open) (struct inode *, struct file *); 1710: int (*flush) (struct file *, fl_owner_t id); 1711: int (*release) (struct inode *, struct file *); 1712: int (*fsync) (struct file *, loff_t, loff_t, int datasync); 1713: int (*fasync) (int, struct file *, int); 1714: int (*lock) (struct file *, int, struct file_lock *); 1715: ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int); 1716: unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); 1717: int (*check_flags)(int); 1718: int (*flock) (struct file *, int, struct file_lock *); 1719: ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); 1720: ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); 1721: int (*setlease)(struct file *, long, struct file_lock **, void **); 1722: long (*fallocate)(struct file *file, int mode, loff_t offset, 1723: loff_t len); 1724: void (*show_fdinfo)(struct seq_file *m, struct file *f); 1725: #ifndef CONFIG_MMU 1726: unsigned (*mmap_capabilities)(struct file *); 1727: #endif 1728: ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, 1729: loff_t, size_t, unsigned int); 1730: int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, 1731: u64); 1732: ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *, 1733: u64); 1734: };主な手続きの意味
linux-4.9.1/include/linux/dcache.h 83: struct dentry { ... 88: struct dentry *d_parent; /* parent directory */ 89: struct qstr d_name; 90: struct inode *d_inode; /* Where the name belongs to - NULL is 91: * negative */ 92: unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ ... 95: struct lockref d_lockref; /* per-dentry lock and refcount */ 96: const struct dentry_operations *d_op; 97: struct super_block *d_sb; /* The root of the dentry tree */ ... 99: void *d_fsdata; /* fs-specific data */ ... 105: struct list_head d_child; /* child of parent list */ 106: struct list_head d_subdirs; /* our children */ ... 115: }; 280: static inline unsigned d_count(const struct dentry *dentry) 281: { 282: return dentry->d_lockref.count; 283: } 31: #define HASH_LEN_DECLARE u32 hash; u32 len 45: struct qstr { 46: union { 47: struct { 48: HASH_LEN_DECLARE; 49: }; 50: u64 hash_len; 51: }; 52: const unsigned char *name; 53: }; 77: # define DNAME_INLINE_LEN 40 /* 128 bytes */
linux-4.9.1/include/linux/fs.h 604: struct inode { 605: umode_t i_mode; 606: unsigned short i_opflags; 607: kuid_t i_uid; 608: kgid_t i_gid; ... 616: const struct inode_operations *i_op; 617: struct super_block *i_sb; ... 637: dev_t i_rdev; 638: loff_t i_size; 639: struct timespec i_atime; 640: struct timespec i_mtime; 641: struct timespec i_ctime; 642: spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ 643: unsigned short i_bytes; 644: unsigned int i_blkbits; 645: blkcnt_t i_blocks; ... 652: unsigned long i_state; ... 658: struct hlist_node i_hash; ... 676: atomic_t i_count; ... 705: void *i_private; /* fs or device private pointer */ 706: };
struct inode *inode; ... inode->i_op->create(inode, name, mode, true);i_op には、次のような手続きがある。各ファイルシステム (ext4,nfs,tmpfs,...) ごとに、手続きの実体は異なるが、インタフェースは同じ。
linux-4.9.1/include/linux/fs.h 1736: struct inode_operations { 1737: struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int); 1738: const char * (*get_link) (struct dentry *, struct inode *, struct delayed_call *); 1739: int (*permission) (struct inode *, int); 1740: struct posix_acl * (*get_acl)(struct inode *, int); 1741: 1742: int (*readlink) (struct dentry *, char __user *,int); 1743: 1744: int (*create) (struct inode *,struct dentry *, umode_t, bool); 1745: int (*link) (struct dentry *,struct inode *,struct dentry *); 1746: int (*unlink) (struct inode *,struct dentry *); 1747: int (*symlink) (struct inode *,struct dentry *,const char *); 1748: int (*mkdir) (struct inode *,struct dentry *,umode_t); 1749: int (*rmdir) (struct inode *,struct dentry *); 1750: int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t); 1751: int (*rename) (struct inode *, struct dentry *, 1752: struct inode *, struct dentry *, unsigned int); 1753: int (*setattr) (struct dentry *, struct iattr *); 1754: int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *); 1755: ssize_t (*listxattr) (struct dentry *, char *, size_t); 1756: int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, 1757: u64 len); 1758: int (*update_time)(struct inode *, struct timespec *, int); 1759: int (*atomic_open)(struct inode *, struct dentry *, 1760: struct file *, unsigned open_flag, 1761: umode_t create_mode, int *opened); 1762: int (*tmpfile) (struct inode *, struct dentry *, umode_t); 1763: int (*set_acl)(struct inode *, struct posix_acl *, int); 1764: } ____cacheline_aligned;
linux-4.9.1/include/linux/fs.h 1338: struct super_block { ... 1343: loff_t s_maxbytes; /* Max file size */ 1344: struct file_system_type *s_type; 1345: const struct super_operations *s_op; ... 1377: void *s_fs_info; /* Filesystem private info */ ... 1432: struct list_lru s_dentry_lru ____cacheline_aligned_in_smp; 1433: struct list_lru s_inode_lru ____cacheline_aligned_in_smp; ... 1446: struct list_head s_inodes; /* all inodes */ ... 1450: };
p->files->fd_array[fd]
の struct file を表
す。
linux-4.9.1/include/linux/sched.h 1475: struct task_struct { ... 1682: struct files_struct *files; ... 1967: }; linux-4.9.1/include/linux/fdtable.h 46: struct files_struct { ... 64: struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 65: }; 22: #define NR_OPEN_DEFAULT BITS_PER_LONG linux-4.9.1/include/asm-generic/bitsperlong.h 7: #ifdef CONFIG_64BIT 8: #define BITS_PER_LONG 64 9: #else 10: #define BITS_PER_LONG 32 11: #endif /* CONFIG_64BIT */
図? task_struct、ファイル記述子、file構造体、その他
linux-4.9.1/fs/read_write.c 584: SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) 585: { 586: struct fd f = fdget_pos(fd); 587: ssize_t ret = -EBADF; 588: 589: if (f.file) { 590: loff_t pos = file_pos_read(f.file); 591: ret = vfs_read(f.file, buf, count, &pos); 592: if (ret >= 0) 593: file_pos_write(f.file, pos); 594: fdput_pos(f); 595: } 596: return ret; 597: } linux-4.9.1/include/linux/file.h 29: struct fd { 30: struct file *file; 31: unsigned int flags; 32: };
linux-4.9.1/fs/read_write.c 460: ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos) 461: { 462: ssize_t ret; 463: 464: if (!(file->f_mode & FMODE_READ)) 465: return -EBADF; 466: if (!(file->f_mode & FMODE_CAN_READ)) 467: return -EINVAL; 468: if (unlikely(!access_ok(VERIFY_WRITE, buf, count))) 469: return -EFAULT; 470: 471: ret = rw_verify_area(READ, file, pos, count); 472: if (!ret) { 473: if (count > MAX_RW_COUNT) 474: count = MAX_RW_COUNT; 475: ret = __vfs_read(file, buf, count, pos); 476: if (ret > 0) { 477: fsnotify_access(file); 478: add_rchar(current, ret); 479: } 480: inc_syscr(current); 481: } 482: 483: return ret; 484: } 448: ssize_t __vfs_read(struct file *file, char __user *buf, size_t count, 449: loff_t *pos) 450: { 451: if (file->f_op->read) 452: return file->f_op->read(file, buf, count, pos); 453: else if (file->f_op->read_iter) 454: return new_sync_read(file, buf, count, pos); 455: else 456: return -EINVAL; 457: } 458: EXPORT_SYMBOL(__vfs_read); 431: static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) 432: { ... 442: ret = filp->f_op->read_iter(&kiocb, &iter); ... 444: *ppos = kiocb.ki_pos; 445: return ret; 446: }
linux-4.9.1/fs/ext4/file.c 688: const struct file_operations ext4_file_operations = { 689: .llseek = ext4_llseek, 690: .read_iter = generic_file_read_iter, 691: .write_iter = ext4_file_write_iter, 692: .unlocked_ioctl = ext4_ioctl, 693: #ifdef CONFIG_COMPAT 694: .compat_ioctl = ext4_compat_ioctl, 695: #endif 696: .mmap = ext4_file_mmap, 697: .open = ext4_file_open, 698: .release = ext4_release_file, 699: .fsync = ext4_sync_file, 700: .get_unmapped_area = thp_get_unmapped_area, 701: .splice_read = generic_file_splice_read, 702: .splice_write = iter_file_splice_write, 703: .fallocate = ext4_fallocate, 704: }; 706: const struct inode_operations ext4_file_inode_operations = { ... 713: }; linux-4.9.1/fs/ext4/super.c 1232: static const struct super_operations ext4_sops = { ... 1252: };
linux-4.9.1/fs/ext4/ext4.h 940: struct ext4_inode_info { ... 1007: struct inode vfs_inode; ... 1082: }; 1531: static inline struct ext4_inode_info *EXT4_I(struct inode *inode) 1532: { 1533: return container_of(inode, struct ext4_inode_info, vfs_inode); 1534: } linux-4.9.1/include/linux/kernel.h 828: /** 829: * container_of - cast a member of a structure out to the containing structure 830: * @ptr: the pointer to the member. 831: * @type: the type of the container struct this is embedded in. 832: * @member: the name of the member within the struct. 833: * 834: */ 835: #define container_of(ptr, type, member) ({ \ 836: const typeof( ((type *)0)->member ) *__mptr = (ptr); \ 837: (type *)( (char *)__mptr - offsetof(type,member) );})
図? Ext4 ファイルシステムで使う構造体 ext4_inode_info での struct inode の保持
linux-4.9.1/mm/filemap.c 1921: generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) 1922: { 1923: struct file *file = iocb->ki_filp; 1924: ssize_t retval = 0; 1925: size_t count = iov_iter_count(iter); ... 1964: retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval); 1965: out: 1966: return retval; 1967: }
1675: static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, 1676: struct iov_iter *iter, ssize_t written) 1677: { 1678: struct address_space *mapping = filp->f_mapping; 1679: struct inode *inode = mapping->host; ... 1681: pgoff_t index; ... 1684: unsigned long offset; /* offset into pagecache page */ ... ... 1686: int error = 0; ... 1692: index = *ppos >> PAGE_SHIFT; ... 1696: offset = *ppos & ~PAGE_MASK; ... 1698: for (;;) { 1699: struct page *page; ... 1702: unsigned long nr, ret; ... 1706: page = find_get_page(mapping, index); 1707: if (!page) { 1708: page_cache_sync_readahead(mapping, 1709: ra, filp, 1710: index, last_index - index); 1711: page = find_get_page(mapping, index); 1712: if (unlikely(page == NULL)) 1713: goto no_cached_page; 1714: } ... 1766: nr = PAGE_SIZE; ... 1774: nr = nr - offset; ... 1796: ret = copy_page_to_iter(page, offset, nr, iter); 1797: offset += ret; 1798: index += offset >> PAGE_SHIFT; 1799: offset &= ~PAGE_MASK; ... 1802: put_page(page); 1803: written += ret; 1804: if (!iov_iter_count(iter)) 1805: goto out; ... 1810: continue; 1900: } 1901: 1902: out: .... 1907: *ppos = ((loff_t)index << PAGE_SHIFT) + offset; 1908: file_accessed(filp); 1909: return written ? written : error; 1910: }
void f(int arg1, int arg2) { 省略; }これを実現するために、どのような Tasklet のハンドラと初期化コードを書け ばよいか。以下の空欄を埋めなさい。
void tasklet_handler(unsigned long data) { /* Tasklet ハンドラ */ int arg1, arg2; arg1 = 省略; arg2 = 省略; /*空欄(a)*/ その他の仕事; } DECLARE_TASKLET(/*空欄(b)*/, /*空欄(c)*/, 0); /* 構造体の初期化 */注意: 構造体の名前は、次の問題の解答で利用する。それらしいものを付けな さい。
irqreturn_t irq_handler(int irq, void *dev) { /*空欄(d)*/ return IRQ_HANDLED; }
int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) { struct inode *inode = file->f_mapping->host; if (!file->f_op->/*空欄(e)*/) return -EINVAL; /*中略*/ return file->f_op->/*空欄(f)*/(/*空欄(g)*/, start, end, datasync); }