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SubjectRe: [PATCH] kdesu broken
Date
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:

> On Mon, Jul 27, 2009 at 05:42:52PM +0100, Alan Cox wrote:
>>
>> > > - if (count > tty->receive_room) {
>> > > + if (count > tty->receive_room)
>> > > count = tty->receive_room;
>> > > - done = 0;
>> > > - }
>> > > char_buf = head->char_buf_ptr + head->read;
>> > > flag_buf = head->flag_buf_ptr + head->read;
>> > > head->read += count;
>> > > _
>> >
>> >
>> > I still have the "compile in emacs" bug. So this patch along with
>> > http://article.gmane.org/gmane.linux.kernel/869824 doesn't fix the
>> > bug for me.
>>
>> Can you stick some printk calls in and debug it further then because at
>> with the fixes Ogawa provided I'm finding it impossible to reproduce even
>> on an 8 way x86.
>>
>> What hardware are you using ?
>
> My T60p lenovo laptop. If you can send me a debug prink patch i can redo the
> test with the patches. I don't know what data i should start collecting so
> that it make sense. This is the patch i tried

If I read that part of emacs correctly, it seems to be assuming the data
was already sent to master side if the child process was exited.

And if it's right, unfortunately, I guess we can't return -EAGAIN in
this case to preserve behavior.

Aneesh, can you get the log of strace of emacs error case?

Thanks.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

#define _GNU_SOURCE
#define BIG_BUF
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <error.h>
#include <limits.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <unistd.h>

static char pts_name[PATH_MAX];

static int open_pty(void)
{
int master;
char *name;
master = getpt();
if (master < 0)
return -1;
if (grantpt(master) < 0 || unlockpt(master) < 0)
goto close_master;
{
int on = 1;
ioctl(master, FIONBIO, &on);
}
name = ptsname(master);
if (name == NULL)
goto close_master;
strcpy(pts_name, name);

return master;

close_master:
close(master);
return -1;
}
static pid_t child(int master)
{
pid_t pid;
int slave;
pid = fork();
if (pid < 0)
error(1, errno, "%s: fork", __func__);
if (pid == 0) {
slave = open(pts_name, O_RDWR);
if (slave < 0)
error(1, errno, "%s: open", __func__);
close(master);
dup2(slave, 0);
dup2(slave, 1);
dup2(slave, 2);
close(slave);

#ifdef BIG_BUF
{
char buf[4096];
size_t size;
memset(buf, '-', sizeof(buf));
size = 0;
while (size < 8192) {
ssize_t r = write(STDOUT_FILENO, buf, sizeof(buf));
if (r < 0)
error(1, errno, "%s: write", __func__);
size += r;
}
}
#else
printf("1-----------------------------------------------\n");
printf("2-----------------------------------------------\n");
printf("3-----------------------------------------------\n");
printf("4-----------------------------------------------\n");
printf("5-----------------------------------------------\n");
printf("6-----------------------------------------------\n");
printf("7-----------------------------------------------\n");
printf("8-----------------------------------------------\n");
printf("9-----------------------------------------------\n");
#endif
exit(0);
}
return pid;
}
int main()
{
pid_t pid;
int master;
master = open_pty();
if (master < 0)
error(1, errno, "%s: open_pty", __func__);
pid = child(master);

waitpid(pid, NULL, 0);
while (1) {
char buf[4096];
ssize_t size;
size = read(master, buf, sizeof(buf));
if (size < 0) {
if (errno == EAGAIN) {
printf("some app doesn't expect EAGAIN\n");
break;
}
error(1, errno, "%s: read", __func__);
}
if (size == 0)
break;
#ifdef BIG_BUF
printf("size %zd\n", size);
#else
write(STDOUT_FILENO, buf, size);
#endif
}
return 0;
}

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