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SubjectRe: Patch?: linux-2.5.59/sound/soundcore.c referenced non-existant errno variable
From
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Hi,

Petr Vandrovec <vandrove@vc.cvut.cz> writes:

> On Fri, Jan 17, 2003 at 08:49:36PM -0600, Raja R Harinath wrote:
>> Hi,
>>
>> "Adam J. Richter" <adam@yggdrasil.com> writes:
>>
>> > linux-2.5.59/sound/sound_firmware.c attempts to use the
>> > user level system call interface from the kernel, which I understand
>> > works on i386 and perhaps all architectures, but requires a variable
>> > named "errno."
>>
>> Which is provided in-kernel (not for modules) by 'lib/errno.c'.
>
> Not safe. We should either remove errno from kernel syscall wrappers
> completely when building __KERNEL__ (just return -1 and nothing more
> specific), or even disallow use of unistd.h wrappers from kernel
> completely (which is best solution IMHO).

__KERNEL_SYSCALLS__ appears to be defined in several files. Don't
know if they actually use any of them.

> BTW, static int errno is by far best solution if you do not agree with
> patch below: due to toolchain behavior soundcore will use its own
> errno for syscall wrappers it uses, and it is nearest to the behavior
> we wanted...
[snip]
> static int do_mod_firmware_load(const char *fn, char **fp)
> {
> - int fd;
> + struct file* filp;
> long l;
> char *dp;
> + loff_t pos;
>
> - fd = open(fn, 0, 0);
> - if (fd == -1)
> + filp = filp_open(fn, 0, 0);
> + if (IS_ERR(filp))
> {
> printk(KERN_INFO "Unable to load '%s'.\n", fn);
> return 0;
> }
[snip]

I noticed that do_mod_firmware_load is wrapped by a
set_fs(get_gs())/set_fs(fs) pair in mod_firmware_load, presumably
because it performs an 'int 0x80' kernel syscall in there. The
cleanup to use the VFS directly should probably kill the wrapper too.

- Hari
--
Raja R Harinath ------------------------------ harinath@cs.umn.edu
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