Function nv_printf

kernel-open/nvidia/os-interface.c:853–900

* nv_printf() prints to the kernel log for the driver. * Returns the number of characters written. */

 * Returns the number of characters written.
 */
int NV_API_CALL nv_printf(NvU32 debuglevel, const char *printf_format, ...)
{
    va_list arglist;
    int chars_written = 0;

    if (debuglevel >= ((cur_debuglevel >> 4) & 0x3))
    {
        size_t length;
        unsigned long flags;

        // When printk is called to extend the output of the previous line
        // (i.e. when the previous line did not end in \n), the printk call
        // must contain KERN_CONT.  Older kernels still print the line
        // correctly, but KERN_CONT was technically always required.

        // This means that every call to printk() needs to have a KERN_xxx
        // prefix.  The only way to get this is to rebuild the format string
        // into a new buffer, with a KERN_xxx prefix prepended.

        // Unfortunately, we can't guarantee that two calls to nv_printf()
        // won't be interrupted by a printk from another driver.  So to be
        // safe, we always append KERN_CONT.  It's still technically wrong,
        // but it works.

        // The long-term fix is to modify all NV_PRINTF-ish calls so that the
        // string always contains only one \n (at the end) and NV_PRINTF_EX
        // is deleted.  But that is unlikely to ever happen.

        length = strlen(printf_format);
        if (length < 1)
            return 0;

        NV_SPIN_LOCK_IRQSAVE(&nv_error_string_lock, flags);

        // KERN_CONT changed in the 3.6 kernel, so we can't assume its
        // composition or size.
        memcpy(nv_error_string, KERN_CONT, sizeof(KERN_CONT) - 1);
        memcpy(nv_error_string + sizeof(KERN_CONT) - 1, printf_format, length + 1);

        va_start(arglist, printf_format);
        chars_written = vprintk(nv_error_string, arglist);
        va_end(arglist);

        NV_SPIN_UNLOCK_IRQRESTORE(&nv_error_string_lock, flags);
    }

    return chars_written;
}

NvS32 NV_API_CALL os_snprintf(char *buf, NvU32 size, const char *fmt, ...)
{