From: Juan Perez-Sanchez <lithoxs@gmail.com>
To: linux-8086 <linux-8086@vger.kernel.org>
Subject: [PATCH 4 OF 5]
Date: Mon, 16 Mar 2015 01:27:38 -0600 [thread overview]
Message-ID: <CAD6VGuZ9QNKbmwLQLYj_LDOmJXU8ZOvZJfr=26e_cM256CdWuw@mail.gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 698 bytes --]
Hi,
This patch implements the behavior of open() and the flag O_NONBLOCK
when opening named pipes.
Moved release of pipe buffers from iput() to pipe_release(). Now,
fs/inode.c knows even less about pipes.
When possible, declared variables and functions in fs/pipe.c as static
and removed their prototypes from fs.h
Pipes can be tested with the following command:
# ls -l /bin | more
Named pipes can be checked with:
# mknod fifo p
# cat /etc/passwd > fifo &
# cat fifo
When you hit enter in the last command, you will see the contents of
file /etc/passwd on screen and then the message of the first 'cat'
exiting. Finally, remove the fifo:
# rm fifo
Code size was increased by 144 bytes.
[-- Attachment #2: elks-3p.patch --]
[-- Type: text/x-patch, Size: 3534 bytes --]
diff -Nur elks.orig/fs/inode.c elks/fs/inode.c
--- elks.orig/fs/inode.c 2015-03-12 12:24:04.000000000 -0600
+++ elks/fs/inode.c 2015-03-12 12:25:35.000000000 -0600
@@ -359,11 +359,6 @@
}
wake_up(&inode_wait);
- if (((inode->i_mode & S_IFMT) == S_IFIFO) && inode->u.pipe_i.base) {
- /* Free up any memory allocated to the pipe */
- free_pipe_mem(inode->u.pipe_i.base);
- inode->u.pipe_i.base = NULL;
- }
if (inode->i_sb) {
struct super_operations *sop = inode->i_sb->s_op;
diff -Nur elks.orig/fs/pipe.c elks/fs/pipe.c
--- elks.orig/fs/pipe.c 2015-03-12 12:24:04.000000000 -0600
+++ elks/fs/pipe.c 2015-03-12 12:33:51.000000000 -0600
@@ -59,11 +59,11 @@
* V7, and they should be buffers
*/
-char pipe_base[MAX_PIPES][PIPE_BUF];
+static char pipe_base[MAX_PIPES][PIPE_BUF];
-int pipe_in_use[(MAX_PIPES + 15)/16];
+static int pipe_in_use[(MAX_PIPES + 15)/16];
-char *get_pipe_mem(void)
+static char *get_pipe_mem(void)
{
int i = 0;
@@ -77,7 +77,7 @@
return NULL;
}
-void free_pipe_mem(char *buf)
+static void free_pipe_mem(char *buf)
{
int i;
@@ -211,7 +211,15 @@
if (filp->f_mode & FMODE_WRITE)
(inode->u.pipe_i.writers)--;
- wake_up_interruptible(&(inode->u.pipe_i.wait));
+ if(!(inode->u.pipe_i.readers + inode->u.pipe_i.writers)) {
+ if(inode->u.pipe_i.base) {
+ /* Free up any memory allocated to the pipe */
+ free_pipe_mem(inode->u.pipe_i.base);
+ inode->u.pipe_i.base = NULL;
+ }
+ }
+ else
+ wake_up_interruptible(&(inode->u.pipe_i.wait));
}
#ifdef STRICT_PIPES
@@ -237,12 +245,6 @@
{
debug("PIPE: rdwr called.\n");
- if (filp->f_mode & FMODE_READ)
- (inode->u.pipe_i.readers)++;
-
- if (filp->f_mode & FMODE_WRITE)
- (inode->u.pipe_i.writers)++;
-
if(!PIPE_BASE(*inode)) {
if(!(PIPE_BASE(*inode) = get_pipe_mem()))
return -ENOMEM;
@@ -254,6 +256,32 @@
PIPE_LOCK(*inode) = 0;
#endif
}
+ if (filp->f_mode & FMODE_READ) {
+ (inode->u.pipe_i.readers)++;
+ if(inode->u.pipe_i.writers > 0) {
+ if(inode->u.pipe_i.readers < 2)
+ wake_up_interruptible(&(inode->u.pipe_i.wait));
+ }
+ else {
+ if(!(filp->f_flags & O_NONBLOCK) && (inode->i_sb))
+ while(!(inode->u.pipe_i.writers))
+ interruptible_sleep_on(&(inode->u.pipe_i.wait));
+ }
+ }
+
+ if (filp->f_mode & FMODE_WRITE) {
+ (inode->u.pipe_i.writers)++;
+ if(inode->u.pipe_i.readers > 0) {
+ if(inode->u.pipe_i.writers < 2)
+ wake_up_interruptible(&(inode->u.pipe_i.wait));
+ }
+ else {
+ if(filp->f_flags & O_NONBLOCK)
+ return -ENXIO;
+ while(!(inode->u.pipe_i.readers))
+ interruptible_sleep_on(&(inode->u.pipe_i.wait));
+ }
+ }
return 0;
}
@@ -320,7 +348,7 @@
/*@+type@*/
-int do_pipe(int *fd)
+static int do_pipe(int *fd)
{
register struct inode *inode;
struct file *f1;
diff -Nur elks.orig/include/linuxmt/fs.h elks/include/linuxmt/fs.h
--- elks.orig/include/linuxmt/fs.h 2015-03-12 12:24:04.000000000 -0600
+++ elks/include/linuxmt/fs.h 2015-03-12 12:34:09.000000000 -0600
@@ -453,7 +453,6 @@
extern int open_namei(char *,int,int,struct inode **,struct inode *);
extern int do_mknod(char *,int,dev_t);
-extern int do_pipe(int *);
extern void iput(struct inode *);
extern struct inode *get_empty_inode(void);
@@ -510,8 +509,6 @@
extern struct buffer_head *bread(dev_t,block_t);
extern int get_unused_fd(struct file *);
-extern char *get_pipe_mem(void);
-extern void free_pipe_mem(char *buf);
extern void mark_buffer_uptodate(struct buffer_head *,int);
next reply other threads:[~2015-03-16 7:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-16 7:27 Juan Perez-Sanchez [this message]
-- strict thread matches above, loose matches on Subject: below --
2014-11-09 19:34 [PATCH 4 of 5] Juan Perez-Sanchez
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