2015年02月05日 情報科学類 オペレーティングシステム II 筑波大学 システム情報工学研究科 コンピュータサイエンス専攻, 電子・情報工学系 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/os2-2014/2015-02-05
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-3.18.1/include/linux/interrupt.h 465: struct tasklet_struct 466: { 467: struct tasklet_struct *next; 468: unsigned long state; 469: atomic_t count; 470: void (*func)(unsigned long); 471: unsigned long data; 472: };
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-3.18.1/drivers/net/wireless/ath/ath9k/ath9k.h 950: struct ath_softc { ... 957: struct tasklet_struct intr_tq; 958: struct tasklet_struct bcon_tasklet; ... 1041: }; linux-3.18.1/drivers/net/wireless/ath/ath9k/init.c 567: tasklet_init(&sc->intr_tq, ath9k_tasklet, (unsigned long)sc); 568: tasklet_init(&sc->bcon_tasklet, ath9k_beacon_tasklet, 569: (unsigned long)sc);
linux-3.18.1/drivers/net/wireless/ath/ath9k/main.c 475: irqreturn_t ath_isr(int irq, void *dev) 476: { ... 496: enum ath9k_int status; ... 524: ath9k_hw_getisr(ah, &status, &sync_cause); /* NB: clears ISR too */ ... 526: status &= ah->imask; /* discard unasked-for bits */ ... 538: if (status & SCHED_INTR) 539: sched = true; ... 562: if (status & ATH9K_INT_SWBA) 563: tasklet_schedule(&sc->bcon_tasklet); ... 590: if (sched) { 591: /* turn off every interrupt */ 592: ath9k_hw_disable_interrupts(ah); 593: tasklet_schedule(&sc->intr_tq); 594: } 595: 596: return IRQ_HANDLED; ... 599: } 358: void ath9k_tasklet(unsigned long data) 359: { ... 473: } linux-3.18.1/drivers/net/wireless/ath/ath9k/beacon.c 315: void ath9k_beacon_tasklet(unsigned long data) 316: { ... 435: }
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-3.18.1/include/linux/workqueue.h 19: typedef void (*work_func_t)(struct work_struct *work); 99: struct work_struct { 100: atomic_long_t data; 101: struct list_head entry; 102: work_func_t func; ... 106: };
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 12 18:11 /usr/bin/perl
-rwxr-xr-x. 2 root root 13304 Nov 12 18:11 /usr/bin/perl5.10.1
$ ls -li /usr/bin/{perl,perl5.10.1}
1837781 -rwxr-xr-x. 2 root root 13304 Nov 12 18:11 /usr/bin/perl
1837781 -rwxr-xr-x. 2 root root 13304 Nov 12 18:11 /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 20 2014 .bashrc
$ stat .bashrc
File: `.bashrc'
Size: 241 Blocks: 16 IO Block: 65536 regular file
Device: 13h/19d Inode: 34824159 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1013/ yas) Gid: ( 510/ prof)
Access: 2015-02-04 06:45:47.000000000 +0900
Modify: 2014-06-20 10:54:23.001388000 +0900
Change: 2014-06-20 10:54:23.001388000 +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-3.18.1/include/linux/fs.h 786: struct file { ... 791: struct path f_path; 792: #define f_dentry f_path.dentry 793: struct inode *f_inode; /* cached value */ 794: const struct file_operations *f_op; ... 801: atomic_long_t f_count; ... 803: fmode_t f_mode; ... 805: loff_t f_pos; ... 815: void *private_data; ... 822: struct address_space *f_mapping; ... 829: unsigned char f_handle[0]; 830: };
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-3.18.1/include/linux/fs.h 1486: struct file_operations { 1487: struct module *owner; 1488: loff_t (*llseek) (struct file *, loff_t, int); 1489: ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); 1490: ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); 1491: ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t); 1492: ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t); 1493: ssize_t (*read_iter) (struct kiocb *, struct iov_iter *); 1494: ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); 1495: int (*iterate) (struct file *, struct dir_context *); 1496: unsigned int (*poll) (struct file *, struct poll_table_struct *); 1497: long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); 1498: long (*compat_ioctl) (struct file *, unsigned int, unsigned long); 1499: int (*mmap) (struct file *, struct vm_area_struct *); 1500: int (*open) (struct inode *, struct file *); 1501: int (*flush) (struct file *, fl_owner_t id); 1502: int (*release) (struct inode *, struct file *); 1503: int (*fsync) (struct file *, loff_t, loff_t, int datasync); 1504: int (*aio_fsync) (struct kiocb *, int datasync); 1505: int (*fasync) (int, struct file *, int); 1506: int (*lock) (struct file *, int, struct file_lock *); 1507: ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int); 1508: unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); 1509: int (*check_flags)(int); 1510: int (*flock) (struct file *, int, struct file_lock *); 1511: ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); 1512: ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); 1513: int (*setlease)(struct file *, long, struct file_lock **, void **); 1514: long (*fallocate)(struct file *file, int mode, loff_t offset, 1515: loff_t len); 1516: int (*show_fdinfo)(struct seq_file *m, struct file *f); 1517: };主な手続きの意味
linux-3.18.1/include/linux/dcache.h 108: struct dentry { ... 113: struct dentry *d_parent; /* parent directory */ 114: struct qstr d_name; 115: struct inode *d_inode; /* Where the name belongs to - NULL is 116: * negative */ 117: unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ ... 120: struct lockref d_lockref; /* per-dentry lock and refcount */ 121: const struct dentry_operations *d_op; 122: struct super_block *d_sb; /* The root of the dentry tree */ ... 124: void *d_fsdata; /* fs-specific data */ ... 127: struct list_head d_child; /* child of parent list */ 128: struct list_head d_subdirs; /* our children */ ... 136: }; 318: static inline unsigned d_count(const struct dentry *dentry) 319: { 320: return dentry->d_lockref.count; 321: } 30: #define HASH_LEN_DECLARE u32 hash; u32 len; 44: struct qstr { ... 47: HASH_LEN_DECLARE; ... 51: const unsigned char *name; 52: }; 102: # define DNAME_INLINE_LEN 40 /* 128 bytes */
linux-3.18.1/include/linux/fs.h 538: struct inode { 539: umode_t i_mode; 540: unsigned short i_opflags; 541: kuid_t i_uid; 542: kgid_t i_gid; ... 550: const struct inode_operations *i_op; 551: struct super_block *i_sb; ... 559: unsigned long i_ino; ... 571: dev_t i_rdev; 572: loff_t i_size; 573: struct timespec i_atime; 574: struct timespec i_mtime; 575: struct timespec i_ctime; 576: spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ 577: unsigned short i_bytes; 578: unsigned int i_blkbits; 579: blkcnt_t i_blocks; ... 586: unsigned long i_state; ... 591: struct hlist_node i_hash; ... 596: struct hlist_head i_dentry; ... 600: atomic_t i_count; ... 626: void *i_private; /* fs or device private pointer */ 627: };
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-3.18.1/include/linux/fs.h 1519: struct inode_operations { 1520: struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int); 1521: void * (*follow_link) (struct dentry *, struct nameidata *); 1522: int (*permission) (struct inode *, int); 1523: struct posix_acl * (*get_acl)(struct inode *, int); 1524: 1525: int (*readlink) (struct dentry *, char __user *,int); 1526: void (*put_link) (struct dentry *, struct nameidata *, void *); 1527: 1528: int (*create) (struct inode *,struct dentry *, umode_t, bool); 1529: int (*link) (struct dentry *,struct inode *,struct dentry *); 1530: int (*unlink) (struct inode *,struct dentry *); 1531: int (*symlink) (struct inode *,struct dentry *,const char *); 1532: int (*mkdir) (struct inode *,struct dentry *,umode_t); 1533: int (*rmdir) (struct inode *,struct dentry *); 1534: int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t); 1535: int (*rename) (struct inode *, struct dentry *, 1536: struct inode *, struct dentry *); 1537: int (*rename2) (struct inode *, struct dentry *, 1538: struct inode *, struct dentry *, unsigned int); 1539: int (*setattr) (struct dentry *, struct iattr *); 1540: int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *); 1541: int (*setxattr) (struct dentry *, const char *,const void *,size_t,int); 1542: ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t); 1543: ssize_t (*listxattr) (struct dentry *, char *, size_t); 1544: int (*removexattr) (struct dentry *, const char *); 1545: int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, 1546: u64 len); 1547: int (*update_time)(struct inode *, struct timespec *, int); 1548: int (*atomic_open)(struct inode *, struct dentry *, 1549: struct file *, unsigned open_flag, 1550: umode_t create_mode, int *opened); 1551: int (*tmpfile) (struct inode *, struct dentry *, umode_t); 1552: int (*set_acl)(struct inode *, struct posix_acl *, int); 1553: 1554: /* WARNING: probably going away soon, do not use! */ 1555: int (*dentry_open)(struct dentry *, struct file *, const struct cred *); 1556: } ____cacheline_aligned;
linux-3.18.1/include/linux/fs.h 1198: struct super_block { ... 1203: loff_t s_maxbytes; /* Max file size */ 1204: struct file_system_type *s_type; 1205: const struct super_operations *s_op; ... 1211: struct dentry *s_root; ... 1220: struct list_head s_inodes; /* all inodes */ ... 1234: void *s_fs_info; /* Filesystem private info */ ... 1282: struct list_lru s_dentry_lru ____cacheline_aligned_in_smp; 1283: struct list_lru s_inode_lru ____cacheline_aligned_in_smp; ... 1290: };
p->files->fd_array[fd]
の struct file を表
す。
linux-3.18.1/include/linux/sched.h 1235: struct task_struct { ... 1416: struct files_struct *files; ... 1664: }; linux-3.18.1/include/linux/fdtable.h 45: struct files_struct { ... 59: struct file __rcu * fd_array[NR_OPEN_DEFAULT]; 60: }; 22: #define NR_OPEN_DEFAULT BITS_PER_LONG linux-3.18.1/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-3.18.1/fs/read_write.c 562: SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) 563: { 564: struct fd f = fdget_pos(fd); 565: ssize_t ret = -EBADF; 566: 567: if (f.file) { 568: loff_t pos = file_pos_read(f.file); 569: ret = vfs_read(f.file, buf, count, &pos); 570: if (ret >= 0) 571: file_pos_write(f.file, pos); 572: fdput_pos(f); 573: } 574: return ret; 575: } linux-3.18.1/include/linux/file.h 29: struct fd { 30: struct file *file; 31: unsigned int flags; 32: };
linux-3.18.1/fs/read_write.c 415: ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos) 416: { 417: ssize_t ret; 418: 419: if (!(file->f_mode & FMODE_READ)) 420: return -EBADF; 421: if (!(file->f_mode & FMODE_CAN_READ)) 422: return -EINVAL; 423: if (unlikely(!access_ok(VERIFY_WRITE, buf, count))) 424: return -EFAULT; 425: 426: ret = rw_verify_area(READ, file, pos, count); 427: if (ret >= 0) { 428: count = ret; 429: if (file->f_op->read) 430: ret = file->f_op->read(file, buf, count, pos); 431: else if (file->f_op->aio_read) 432: ret = do_sync_read(file, buf, count, pos); 433: else 434: ret = new_sync_read(file, buf, count, pos); 435: if (ret > 0) { 436: fsnotify_access(file); 437: add_rchar(current, ret); 438: } 439: inc_syscr(current); 440: } 441: 442: return ret; 443: }
linux-3.18.1/fs/ext4/file.c 584: const struct file_operations ext4_file_operations = { 585: .llseek = ext4_llseek, 586: .read = new_sync_read, 587: .write = new_sync_write, 588: .read_iter = generic_file_read_iter, 589: .write_iter = ext4_file_write_iter, 590: .unlocked_ioctl = ext4_ioctl, 591: #ifdef CONFIG_COMPAT 592: .compat_ioctl = ext4_compat_ioctl, 593: #endif 594: .mmap = ext4_file_mmap, 595: .open = ext4_file_open, 596: .release = ext4_release_file, 597: .fsync = ext4_sync_file, 598: .splice_read = generic_file_splice_read, 599: .splice_write = iter_file_splice_write, 600: .fallocate = ext4_fallocate, 601: }; 603: const struct inode_operations ext4_file_inode_operations = { ... 613: }; linux-3.18.1/fs/ext4/super.c 1103: static const struct super_operations ext4_sops = { ... 1122: };
linux-3.18.1/fs/ext4/ext4.h 816: struct ext4_inode_info { ... 874: struct inode vfs_inode; ... 946: }; 1351: static inline struct ext4_inode_info *EXT4_I(struct inode *inode) 1352: { 1353: return container_of(inode, struct ext4_inode_info, vfs_inode); 1354: } linux-3.18.1/include/linux/kernel.h 788: /** 789: * container_of - cast a member of a structure out to the containing structure 790: * @ptr: the pointer to the member. 791: * @type: the type of the container struct this is embedded in. 792: * @member: the name of the member within the struct. 793: * 794: */ 795: #define container_of(ptr, type, member) ({ \ 796: const typeof( ((type *)0)->member ) *__mptr = (ptr); \ 797: (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-3.18.1/fs/read_write.c 394: ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) 395: { 396: struct iovec iov = { .iov_base = buf, .iov_len = len }; 397: struct kiocb kiocb; 398: struct iov_iter iter; 399: ssize_t ret; 400: 401: init_sync_kiocb(&kiocb, filp); 402: kiocb.ki_pos = *ppos; 403: kiocb.ki_nbytes = len; 404: iov_iter_init(&iter, READ, &iov, 1, len); 405: 406: ret = filp->f_op->read_iter(&kiocb, &iter); 407: if (-EIOCBQUEUED == ret) 408: ret = wait_on_sync_kiocb(&kiocb); 409: *ppos = kiocb.ki_pos; 410: return ret; 411: }
linux-3.18.1/mm/filemap.c 694: ssize_t 1695: generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) 1696: { 1697: struct file *file = iocb->ki_filp; 1698: ssize_t retval = 0; 1699: loff_t *ppos = &iocb->ki_pos; 1700: loff_t pos = *ppos; ... 1738: retval = do_generic_file_read(file, ppos, iter, retval); 1739: out: 1740: return retval; 1741: } 1467: static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos, 1468: struct iov_iter *iter, ssize_t written) 1469: { 1470: struct address_space *mapping = filp->f_mapping; 1471: struct inode *inode = mapping->host; ... 1473: pgoff_t index; ... 1476: unsigned long offset; /* offset into pagecache page */ ... 1478: int error = 0; 1479: 1480: index = *ppos >> PAGE_CACHE_SHIFT; ... 1484: offset = *ppos & ~PAGE_CACHE_MASK; 1485: 1486: for (;;) { 1487: struct page *page; ... 1490: unsigned long nr, ret; ... 1494: page = find_get_page(mapping, index); 1495: if (!page) { 1496: page_cache_sync_readahead(mapping, 1497: ra, filp, 1498: index, last_index - index); 1499: page = find_get_page(mapping, index); ... 1502: } ... 1539: /* nr is the maximum number of bytes to copy from this page */ 1540: nr = PAGE_CACHE_SIZE; ... 1548: nr = nr - offset; ... 1570: ret = copy_page_to_iter(page, offset, nr, iter); 1571: offset += ret; 1572: index += offset >> PAGE_CACHE_SHIFT; 1573: offset &= ~PAGE_CACHE_MASK; ... 1576: page_cache_release(page); 1577: written += ret; 1578: if (!iov_iter_count(iter)) 1579: goto out; 1584: continue; ... 1674: } 1675: 1676: out: ... 1681: *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; 1682: file_accessed(filp); 1683: return written ? written : error; 1684: }
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; }
ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) { ssize_t ret; ... ret = rw_verify_area(WRITE, file, pos, count); if (ret >= 0) { count = ret; file_start_write(file); if (file->f_op->/*空欄(e)*/) ret = file->f_op->/*空欄(f)*/(/*空欄(g)*/, buf, count, pos); ... inc_syscw(current); file_end_write(file); } return ret; }