[uml-devel] Re: Bug#260111: user-mode-linux: upgrade hangs at "NET4: Linux TCP/IP 1.0 for NET4.0 "

[Allen Chan <alydar@users.sourceforge.net>]

More details on the problem after some more investigation and 
testing... the specific function that was moved from chan_user.c to 
chan_kern.c that caused the problem is generic_console_write().  
Notice the isatty() calls.  They probably explain the earlier 
observation that piping or redirecting the stdout gets around the 
problem.

int generic_console_write(int fd, const char *buf, int n, void 
*unused)
{
        struct termios save, new;
        int err;

        if(isatty(fd)){
                tcgetattr(fd, &save);
                new = save;
                new.c_oflag |= OPOST;
                tcsetattr(fd, TCSAFLUSH, &new);
        }
        err = generic_write(fd, buf, n, NULL);
        if(isatty(fd)) tcsetattr(fd, TCSAFLUSH, &save);
        return(err);
}

Note also the output for chan_kern.c while the kernel is compiling:

gcc -D__KERNEL__ -I/home/alydar/play/kernel/linux-2.4.26/include -Wall 
-Wstrict-prototypes -Wno-trigraphs -O2 -fno-strict-aliasing 
-fno-common  -U__i386__ -Ui386 -DUM_FASTCALL -g -D__arch_um__ 
-DSUBARCH="i386" -D_LARGEFILE64_SOURCE 
-I/home/alydar/play/kernel/linux-2.4.26/arch/um/include 
-Derrno=kernel_errno 
-I/home/alydar/play/kernel/linux-2.4.26/arch/um/kernel/tt/include 
-I/home/alydar/play/kernel/linux-2.4.26/arch/um/kernel/skas/include    
-nostdinc -iwithprefix include -DKBUILD_BASENAME=chan_kern  -c -o 
chan_kern.o chan_kern.c
chan_kern.c: In function `generic_console_write':
chan_kern.c:121: warning: implicit declaration of function `isatty'
chan_kern.c:122: warning: implicit declaration of function `tcgetattr'
chan_kern.c:125: warning: implicit declaration of function `tcsetattr'


On Thursday 29 July 2004 02:30 pm, Allen Chan wrote:
>
> It turns out that the following changes caused the problem to show
> up:
>
> arch/um/drivers/chan_kern.c 1.39 Fri 07-16-2004 02:27 PM EDT jdike
> Exp +65 -0
>   Moved some non-userspace code from chan_user.c to chan_kern.c.
> arch/um/drivers/chan_user.c 1.33 Fri 07-16-2004 02:27 PM EDT jdike
> Exp +0 -64
>   Moved some non-userspace code from chan_user.c to chan_kern.c.
>


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