sg.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 2,278 行 · 第 1/5 页

/*
 *  History:
 *  Started: Aug 9 by Lawrence Foard ([e-mail]),
 *           to allow user process control of SCSI devices.
 *  Development Sponsored by Killy Corp. NY NY
 *
 * Original driver (sg.c):
 *        Copyright (C) 1992 Lawrence Foard
 * Version 2 and 3 extensions to driver:
 *        Copyright (C) 1998 - 2004 Douglas Gilbert
 *
 *  Modified  19-JAN-1998  Richard Gooch <[e-mail]>  Devfs support
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 */

static int sg_version_num = 30531;	/* 2 digits for each component */
#define SG_VERSION_STR "3.5.31"

/*
 *  D. P. Gilbert ([e-mail], [e-mail]), notes:
 *      - scsi logging is available via SCSI_LOG_TIMEOUT macros. First
 *        the kernel/module needs to be built with CONFIG_SCSI_LOGGING
 *        (otherwise the macros compile to empty statements).
 *
 */
#include <linux/config.h>
#include <linux/module.h>

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/mtio.h>
#include <linux/ioctl.h>
#include <linux/fcntl.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/smp_lock.h>
#include <linux/moduleparam.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/cdev.h>
#include <linux/seq_file.h>
#include <linux/blkdev.h>
#include <linux/delay.h>

#include "scsi.h"
#include <scsi/scsi_host.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/sg.h>

#include "scsi_logging.h"

#ifdef CONFIG_SCSI_PROC_FS
#include <linux/proc_fs.h>
static char *sg_version_date = "20040516";

static int sg_proc_init(void);
static void sg_proc_cleanup(void);
#endif

#ifndef LINUX_VERSION_CODE
#include <linux/version.h>
#endif				/* LINUX_VERSION_CODE */

#define SG_ALLOW_DIO_DEF 0
#define SG_ALLOW_DIO_CODE /* compile out by commenting this define */

#define SG_MAX_DEVS 32768

/*
 * Suppose you want to calculate the formula muldiv(x,m,d)=int(x * m / d)
 * Then when using 32 bit integers x * m may overflow during the calculation.
 * Replacing muldiv(x) by muldiv(x)=((x % d) * m) / d + int(x / d) * m
 * calculates the same, but prevents the overflow when both m and d
 * are "small" numbers (like HZ and USER_HZ).
 * Of course an overflow is inavoidable if the result of muldiv doesn't fit
 * in 32 bits.
 */
#define MULDIV(X,MUL,DIV) ((((X % DIV) * MUL) / DIV) + ((X / DIV) * MUL))

#define SG_DEFAULT_TIMEOUT MULDIV(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)

int sg_big_buff = SG_DEF_RESERVED_SIZE;
/* N.B. This variable is readable and writeable via
   /proc/scsi/sg/def_reserved_size . Each time sg_open() is called a buffer
   of this size (or less if there is not enough memory) will be reserved
   for use by this file descriptor. [Deprecated usage: this variable is also
   readable via /proc/sys/kernel/sg-big-buff if the sg driver is built into
   the kernel (i.e. it is not a module).] */
static int def_reserved_size = -1;	/* picks up init parameter */
static int sg_allow_dio = SG_ALLOW_DIO_DEF;

#define SG_SECTOR_SZ 512
#define SG_SECTOR_MSK (SG_SECTOR_SZ - 1)

#define SG_DEV_ARR_LUMP 32	/* amount to over allocate sg_dev_arr by */

static int sg_add(struct class_device *);
static void sg_remove(struct class_device *);

static Scsi_Request *dummy_cmdp;	/* only used for sizeof */

static rwlock_t sg_dev_arr_lock = RW_LOCK_UNLOCKED;	/* Also used to lock
							   file descriptor list for device */

static struct class_interface sg_interface = {
	.add		= sg_add,
	.remove		= sg_remove,
};

typedef struct sg_scatter_hold { /* holding area for scsi scatter gather info */
	unsigned short k_use_sg; /* Count of kernel scatter-gather pieces */
	unsigned short sglist_len; /* size of malloc'd scatter-gather list ++ */
	unsigned bufflen;	/* Size of (aggregate) data buffer */
	unsigned b_malloc_len;	/* actual len malloc'ed in buffer */
	void *buffer;		/* Data buffer or scatter list (k_use_sg>0) */
	char dio_in_use;	/* 0->indirect IO (or mmap), 1->dio */
	unsigned char cmd_opcode; /* first byte of command */
} Sg_scatter_hold;

struct sg_device;		/* forward declarations */
struct sg_fd;

typedef struct sg_request {	/* SG_MAX_QUEUE requests outstanding per file */
	Scsi_Request *my_cmdp;	/* != 0  when request with lower levels */
	struct sg_request *nextrp;	/* NULL -> tail request (slist) */
	struct sg_fd *parentfp;	/* NULL -> not in use */
	Sg_scatter_hold data;	/* hold buffer, perhaps scatter list */
	sg_io_hdr_t header;	/* scsi command+info, see <scsi/sg.h> */
	unsigned char sense_b[sizeof (dummy_cmdp->sr_sense_buffer)];
	char res_used;		/* 1 -> using reserve buffer, 0 -> not ... */
	char orphan;		/* 1 -> drop on sight, 0 -> normal */
	char sg_io_owned;	/* 1 -> packet belongs to SG_IO */
	volatile char done;	/* 0->before bh, 1->before read, 2->read */
} Sg_request;

typedef struct sg_fd {		/* holds the state of a file descriptor */
	struct sg_fd *nextfp;	/* NULL when last opened fd on this device */
	struct sg_device *parentdp;	/* owning device */
	wait_queue_head_t read_wait;	/* queue read until command done */
	rwlock_t rq_list_lock;	/* protect access to list in req_arr */
	int timeout;		/* defaults to SG_DEFAULT_TIMEOUT      */
	int timeout_user;	/* defaults to SG_DEFAULT_TIMEOUT_USER */
	Sg_scatter_hold reserve;	/* buffer held for this file descriptor */
	unsigned save_scat_len;	/* original length of trunc. scat. element */
	Sg_request *headrp;	/* head of request slist, NULL->empty */
	struct fasync_struct *async_qp;	/* used by asynchronous notification */
	Sg_request req_arr[SG_MAX_QUEUE];	/* used as singly-linked list */
	char low_dma;		/* as in parent but possibly overridden to 1 */
	char force_packid;	/* 1 -> pack_id input to read(), 0 -> ignored */
	volatile char closed;	/* 1 -> fd closed but request(s) outstanding */
	char cmd_q;		/* 1 -> allow command queuing, 0 -> don't */
	char next_cmd_len;	/* 0 -> automatic (def), >0 -> use on next write() */
	char keep_orphan;	/* 0 -> drop orphan (def), 1 -> keep for read() */
	char mmap_called;	/* 0 -> mmap() never called on this fd */
} Sg_fd;

typedef struct sg_device { /* holds the state of each scsi generic device */
	struct scsi_device *device;
	wait_queue_head_t o_excl_wait;	/* queue open() when O_EXCL in use */
	int sg_tablesize;	/* adapter's max scatter-gather table size */
	Sg_fd *headfp;		/* first open fd belonging to this device */
	volatile char detached;	/* 0->attached, 1->detached pending removal */
	volatile char exclude;	/* opened for exclusive access */
	char sgdebug;		/* 0->off, 1->sense, 9->dump dev, 10-> all devs */
	struct gendisk *disk;
	struct cdev * cdev;	/* char_dev [sysfs: /sys/cdev/major/sg<n>] */
} Sg_device;

static int sg_fasync(int fd, struct file *filp, int mode);
static void sg_cmd_done(Scsi_Cmnd * SCpnt);	/* tasklet or soft irq callback */
static int sg_start_req(Sg_request * srp);
static void sg_finish_rem_req(Sg_request * srp);
static int sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size);
static int sg_build_sgat(Sg_scatter_hold * schp, const Sg_fd * sfp,
			 int tablesize);
static ssize_t sg_new_read(Sg_fd * sfp, char __user *buf, size_t count,
			   Sg_request * srp);
static ssize_t sg_new_write(Sg_fd * sfp, const char __user *buf, size_t count,
			    int blocking, int read_only, Sg_request ** o_srp);
static int sg_common_write(Sg_fd * sfp, Sg_request * srp,
			   unsigned char *cmnd, int timeout, int blocking);
static int sg_u_iovec(sg_io_hdr_t * hp, int sg_num, int ind,
		      int wr_xf, int *countp, unsigned char __user **up);
static int sg_write_xfer(Sg_request * srp);
static int sg_read_xfer(Sg_request * srp);
static int sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer);
static void sg_remove_scat(Sg_scatter_hold * schp);
static void sg_build_reserve(Sg_fd * sfp, int req_size);
static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size);
static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp);
static char *sg_page_malloc(int rqSz, int lowDma, int *retSzp);
static void sg_page_free(char *buff, int size);
static Sg_fd *sg_add_sfp(Sg_device * sdp, int dev);
static int sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp);
static void __sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp);
static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id);
static Sg_request *sg_add_request(Sg_fd * sfp);
static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
static int sg_res_in_use(Sg_fd * sfp);
static int sg_allow_access(unsigned char opcode, char dev_type);
static int sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len);
static Sg_device *sg_get_dev(int dev);
static inline unsigned char *sg_scatg2virt(const struct scatterlist *sclp);
#ifdef CONFIG_SCSI_PROC_FS
static int sg_last_dev(void);
#endif

static Sg_device **sg_dev_arr = NULL;
static int sg_dev_max;
static int sg_nr_dev;

#define SZ_SG_HEADER sizeof(struct sg_header)
#define SZ_SG_IO_HDR sizeof(sg_io_hdr_t)
#define SZ_SG_IOVEC sizeof(sg_iovec_t)
#define SZ_SG_REQ_INFO sizeof(sg_req_info_t)

static int
sg_open(struct inode *inode, struct file *filp)
{
	int dev = iminor(inode);
	int flags = filp->f_flags;
	Sg_device *sdp;
	Sg_fd *sfp;
	int res;
	int retval;

	nonseekable_open(inode, filp);
	SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags));
	sdp = sg_get_dev(dev);
	if ((!sdp) || (!sdp->device))
		return -ENXIO;
	if (sdp->detached)
		return -ENODEV;

	/* This driver's module count bumped by fops_get in <linux/fs.h> */
	/* Prevent the device driver from vanishing while we sleep */
	retval = scsi_device_get(sdp->device);
	if (retval)
		return retval;

	if (!((flags & O_NONBLOCK) ||
	      scsi_block_when_processing_errors(sdp->device))) {
		retval = -ENXIO;
		/* we are in error recovery for this device */
		goto error_out;
	}

	if (flags & O_EXCL) {
		if (O_RDONLY == (flags & O_ACCMODE)) {
			retval = -EPERM; /* Can't lock it with read only access */
			goto error_out;
		}
		if (sdp->headfp && (flags & O_NONBLOCK)) {
			retval = -EBUSY;
			goto error_out;
		}
		res = 0;
		__wait_event_interruptible(sdp->o_excl_wait,
			((sdp->headfp || sdp->exclude) ? 0 : (sdp->exclude = 1)), res);
		if (res) {
			retval = res;	/* -ERESTARTSYS because signal hit process */
			goto error_out;
		}
	} else if (sdp->exclude) {	/* some other fd has an exclusive lock on dev */
		if (flags & O_NONBLOCK) {
			retval = -EBUSY;
			goto error_out;
		}
		res = 0;
		__wait_event_interruptible(sdp->o_excl_wait, (!sdp->exclude),
					   res);
		if (res) {
			retval = res;	/* -ERESTARTSYS because signal hit process */
			goto error_out;
		}
	}
	if (sdp->detached) {
		retval = -ENODEV;
		goto error_out;
	}
	if (!sdp->headfp) {	/* no existing opens on this device */
		sdp->sgdebug = 0;
		sdp->sg_tablesize = sdp->device->host->sg_tablesize;
	}
	if ((sfp = sg_add_sfp(sdp, dev)))
		filp->private_data = sfp;
	else {
		if (flags & O_EXCL)
			sdp->exclude = 0;	/* undo if error */
		retval = -ENOMEM;
		goto error_out;
	}
	return 0;

      error_out:
	scsi_device_put(sdp->device);
	return retval;
}

/* Following function was formerly called 'sg_close' */
static int
sg_release(struct inode *inode, struct file *filp)
{
	Sg_device *sdp;
	Sg_fd *sfp;

	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
		return -ENXIO;
	SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name));
	sg_fasync(-1, filp, 0);	/* remove filp from async notification list */
	if (0 == sg_remove_sfp(sdp, sfp)) {	/* Returns 1 when sdp gone */
		if (!sdp->detached) {
			scsi_device_put(sdp->device);
		}
		sdp->exclude = 0;
		wake_up_interruptible(&sdp->o_excl_wait);
	}
	return 0;
}

static ssize_t
sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
{
	int k, res;
	Sg_device *sdp;
	Sg_fd *sfp;
	Sg_request *srp;
	int req_pack_id = -1;
	struct sg_header old_hdr;
	sg_io_hdr_t new_hdr;
	sg_io_hdr_t *hp;

	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
		return -ENXIO;
	SCSI_LOG_TIMEOUT(3, printk("sg_read: %s, count=%d\n",
				   sdp->disk->disk_name, (int) count));
	if ((k = verify_area(VERIFY_WRITE, buf, count)))
		return k;
	if (sfp->force_packid && (count >= SZ_SG_HEADER)) {
		if (__copy_from_user(&old_hdr, buf, SZ_SG_HEADER))
			return -EFAULT;
		if (old_hdr.reply_len < 0) {
			if (count >= SZ_SG_IO_HDR) {
				if (__copy_from_user
				    (&new_hdr, buf, SZ_SG_IO_HDR))
					return -EFAULT;
				req_pack_id = new_hdr.pack_id;
			}
		} else
			req_pack_id = old_hdr.pack_id;
	}
	srp = sg_get_rq_mark(sfp, req_pack_id);
	if (!srp) {		/* now wait on packet to arrive */
		if (sdp->detached)
			return -ENODEV;
		if (filp->f_flags & O_NONBLOCK)
			return -EAGAIN;
		while (1) {
			res = 0;	/* following is a macro that beats race condition */
			__wait_event_interruptible(sfp->read_wait,
				(sdp->detached || (srp = sg_get_rq_mark(sfp, req_pack_id))), 
						   res);
			if (sdp->detached)
				return -ENODEV;
			if (0 == res)
				break;
			return res;	/* -ERESTARTSYS because signal hit process */
		}
	}
	if (srp->header.interface_id != '\0')
		return sg_new_read(sfp, buf, count, srp);

	hp = &srp->header;
	memset(&old_hdr, 0, SZ_SG_HEADER);
	old_hdr.reply_len = (int) hp->timeout;
	old_hdr.pack_len = old_hdr.reply_len; /* very old, strange behaviour */
	old_hdr.pack_id = hp->pack_id;
	old_hdr.twelve_byte =
	    ((srp->data.cmd_opcode >= 0xc0) && (12 == hp->cmd_len)) ? 1 : 0;
	old_hdr.target_status = hp->masked_status;
	old_hdr.host_status = hp->host_status;
	old_hdr.driver_status = hp->driver_status;
	if ((CHECK_CONDITION & hp->masked_status) ||
	    (DRIVER_SENSE & hp->driver_status))
		memcpy(old_hdr.sense_buffer, srp->sense_b,
		       sizeof (old_hdr.sense_buffer));
	switch (hp->host_status) {
	/* This setup of 'result' is for backward compatibility and is best
	   ignored by the user who should use target, host + driver status */
	case DID_OK:
	case DID_PASSTHROUGH:
	case DID_SOFT_ERROR:
		old_hdr.result = 0;
		break;
	case DID_NO_CONNECT:
	case DID_BUS_BUSY:
	case DID_TIME_OUT:
		old_hdr.result = EBUSY;
		break;
	case DID_BAD_TARGET:
	case DID_ABORT:
	case DID_PARITY:
	case DID_RESET:
	case DID_BAD_INTR:
		old_hdr.result = EIO;
		break;
	case DID_ERROR:
		old_hdr.result = (srp->sense_b[0] == 0 && 
				  hp->masked_status == GOOD) ? 0 : EIO;
		break;
	default:
		old_hdr.result = EIO;
		break;
	}

	/* Now copy the result back to the user buffer.  */
	if (count >= SZ_SG_HEADER) {
		if (__copy_to_user(buf, &old_hdr, SZ_SG_HEADER))
			return -EFAULT;
		buf += SZ_SG_HEADER;
		if (count > old_hdr.reply_len)
			count = old_hdr.reply_len;
		if (count > SZ_SG_HEADER) {
			if ((res =
			     sg_read_oxfer(srp, buf, count - SZ_SG_HEADER)))
				return -EFAULT;
		}
	} else
		count = (old_hdr.result == 0) ? 0 : -EIO;
	sg_finish_rem_req(srp);
	return count;
}

static ssize_t
sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp)
{
	sg_io_hdr_t *hp = &srp->header;
	int err = 0;
	int len;

	if (count < SZ_SG_IO_HDR) {
		err = -EINVAL;
		goto err_out;
	}
	hp->sb_len_wr = 0;
	if ((hp->mx_sb_len > 0) && hp->sbp) {
		if ((CHECK_CONDITION & hp->masked_status) ||