8e18e2941c
The following patches reduce the size of the VFS inode structure by 28 bytes on a UP x86. (It would be more on an x86_64 system). This is a 10% reduction in the inode size on a UP kernel that is configured in a production mode (i.e., with no spinlock or other debugging functions enabled; if you want to save memory taken up by in-core inodes, the first thing you should do is disable the debugging options; they are responsible for a huge amount of bloat in the VFS inode structure). This patch: The filesystem or device-specific pointer in the inode is inside a union, which is pretty pointless given that all 30+ users of this field have been using the void pointer. Get rid of the union and rename it to i_private, with a comment to explain who is allowed to use the void pointer. This is just a cleanup, but it allows us to reuse the union 'u' for something something where the union will actually be used. [judith@osdl.org: powerpc build fix] Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Judith Lebzelter <judith@osdl.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
75 lines
1.5 KiB
C
75 lines
1.5 KiB
C
/*
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* The USB Monitor, inspired by Dave Harding's USBMon.
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*
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* This is the 's' or 'stat' reader which debugs usbmon itself.
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* Note that this code blows through locks, so make sure that
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* /dbg/usbmon/0s is well protected from non-root users.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/usb.h>
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#include <asm/uaccess.h>
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#include "usb_mon.h"
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#define STAT_BUF_SIZE 80
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struct snap {
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int slen;
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char str[STAT_BUF_SIZE];
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};
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static int mon_stat_open(struct inode *inode, struct file *file)
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{
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struct mon_bus *mbus;
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struct snap *sp;
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if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
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return -ENOMEM;
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mbus = inode->i_private;
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sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
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"nreaders %d events %u text_lost %u\n",
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mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
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file->private_data = sp;
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return 0;
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}
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static ssize_t mon_stat_read(struct file *file, char __user *buf,
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size_t nbytes, loff_t *ppos)
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{
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struct snap *sp = file->private_data;
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loff_t pos = *ppos;
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int cnt;
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if (pos < 0 || pos >= sp->slen)
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return 0;
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if (nbytes == 0)
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return 0;
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if ((cnt = sp->slen - pos) > nbytes)
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cnt = nbytes;
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if (copy_to_user(buf, sp->str + pos, cnt))
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return -EFAULT;
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*ppos = pos + cnt;
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return cnt;
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}
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static int mon_stat_release(struct inode *inode, struct file *file)
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{
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return 0;
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}
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struct file_operations mon_fops_stat = {
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.owner = THIS_MODULE,
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.open = mon_stat_open,
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.llseek = no_llseek,
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.read = mon_stat_read,
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/* .write = mon_stat_write, */
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/* .poll = mon_stat_poll, */
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/* .ioctl = mon_stat_ioctl, */
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.release = mon_stat_release,
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};
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