patch for errno-issue (with soundcore)

There is no problem currently, because of nobody uses errno value at all (in the firmware loader), it is just that inline functions generated by syscallX() store error codes into errno...

Real problem is that firmware loader should use filp_open/vfs_read/filp_close (or sys_open/sys_llseek/sys_read/sys_close if you want to use fd interface, but filp_{open,close} and vfs_read are already exported for modules while sys_open/sys_llseek/sys_read are not).

As an alternative, do_mod_firmware_load should be standalone userspace program executed through call_usermodehelper or something like that... Unfortunately we do not have an interface to distribute userspace binaries together with kernel (except initrd) yet, so it would require either adding do_mod_firmware_load into module-init-tools, or some simillar package required by 2.[56].x kernels.

Also adding "#define errno (current()->exit_code)" at the beginning of sound_firmware.c (just below #define __KERNEL_SYSCALLS__) should do the trick, but I do not recommend taking this path.
Best regards,
Petr Vandrovec [email protected]

First of all a big THANKS!

Now, at least, I understood the real problem...
'errno' is only needed because open(), close(), llseek() and read() are used, which do a syscall and the return code is written to a variable called 'errno'. This is NOT the 'errno' variable defined in lib/errno.c... OK.

And so the real problem is using these functions and as we ARE in the kernel mode we do not really need the kernel traps...

So after realizing the real problem I think I am not the right person to fix it. But if you want I could try...

Sincerely yours
Thomas Schlichter

Hi,
can someone with sound card requiring firmware download (OSS's trix,
sb_common, msnd_pinnacle, sscape, maui or pss) verify that code below works? I know that it compiles without warnings, and looks obviously correct (to me), but...

I think that I do not need any locking around reading i_size, as
nothing bad should happen if size changes, you'll get damaged firmware upload at worst, and if you are updating firmware file while kernel reads it, you deserve it (besides that vfs_read is one who will do final check). And sys_stat (getattr) does not take any lock too, unless I missed something.

Patch is for 2.5.57.

BTW, should I convert it to goto? It was really annoying that I had to
fix 3 error paths instead of one ;-)
Best regards,
Petr Vandrovec [email protected]

diff -urdN linux/sound/sound_firmware.c linux/sound/sound_firmware.c
@@ -9,39 +9,40 @@
 
 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;
 	}
-	l = lseek(fd, 0L, 2);
+	l = filp->f_dentry->d_inode->i_size;
 	if (l <= 0 || l > 131072)
 	{
 		printk(KERN_INFO "Invalid firmware '%s'\n", fn);
-		sys_close(fd);
+		filp_close(filp, current->files);
 		return 0;
 	}
-	lseek(fd, 0L, 0);
 	dp = vmalloc(l);
 	if (dp == NULL)
 	{
 		printk(KERN_INFO "Out of memory loading '%s'.\n", fn);
-		sys_close(fd);
+		filp_close(filp, current->files);
 		return 0;
 	}
-	if (read(fd, dp, l) != l)
+	pos = 0;
+	if (vfs_read(filp, dp, l, &pos) != l)
 	{
 		printk(KERN_INFO "Failed to read '%s'.\n", fn);
 		vfree(dp);
-		sys_close(fd);
+		filp_close(filp, current->files);
 		return 0;
 	}
-	close(fd);
+	filp_close(filp, current->files);
 	*fp = dp;
 	return (int) l;
 }