Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 20 Apr 2001 19:17:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 20 Apr 2001 19:17:41 -0400 Received: from diup-184-214.inter.net.il ([213.8.184.214]:4100 "EHLO callisto.yi.org") by vger.kernel.org with ESMTP id ; Fri, 20 Apr 2001 19:17:34 -0400 Date: Sat, 21 Apr 2001 02:17:18 +0300 (IDT) From: Dan Aloni To: linux-kernel cc: Jens Axboe Subject: cdrom driver dependency problem (and a workaround patch) Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Between 2.4.3-ac9 and 2.4.3-ac10 the CDROM Uniform Driver was modified. The modification added a dependency of the *register_cdrom() functions on the cdrom_init() function. Theoretically, cdrom_init() should have been called before any call to register_cdrom(). But practically, when the CDROM driver is compiled into the kernel and not as a module, it doesn't happen, and in 2.4.3-ac10 you get an Oops in cdrom_get_entry(), where the NULL cdrom_numbers gets dereferenced. One reason for this misdependency is that the IDE is initialized before the cdrom driver, register_cdrom() gets called from inside the IDE initialization functions. (ide_init() -> ide_init_builtin_drivers() -> ide_cdrom_init() -> ide_cdrom_setup() -> ide_cdrom_register() -> register_cdrom()) In order to get my kernel to boot, I've made the following temporary workaround patch. I'd be glad to hear about other ways of solving this. --- linux-2.4.3-ac10/drivers/cdrom/cdrom.c Fri Apr 20 23:38:37 2001 +++ linux-2.4.3-ac10/drivers/cdrom/cdrom.c Sat Apr 21 01:59:35 2001 @@ -277,6 +277,7 @@ static int autoclose=1; static int autoeject; static int lockdoor = 1; +static int initialized; /* will we ever get to use this... sigh. */ static int check_media_type; static unsigned long *cdrom_numbers; @@ -332,6 +333,9 @@ #ifdef CONFIG_SYSCTL static void cdrom_sysctl_register(void); #endif /* CONFIG_SYSCTL */ + +static int check_cdrom_init(void); + static struct cdrom_device_info *topCdromPtr; static devfs_handle_t devfs_handle; @@ -350,6 +354,8 @@ { int i, nr, foo; + printk("Holly damn. cdrom_numbers=0x%p\n",cdrom_numbers); + nr = 0; foo = -1; for (i = 0; i < CDROM_MAX_CDROMS / (sizeof(unsigned long) * 8); i++) { @@ -368,7 +374,7 @@ static void cdrom_clear_entry(struct cdrom_device_info *cdi) { - int bit_nr = cdi->nr & ~(sizeof(unsigned long) * 8); + int bit_nr = cdi->nr % (sizeof(unsigned long) * 8); int cd_index = cdi->nr / (sizeof(unsigned long) * 8); clear_bit(bit_nr, &cdrom_numbers[cd_index]); @@ -388,10 +394,14 @@ int major = MAJOR(cdi->dev); struct cdrom_device_ops *cdo = cdi->ops; int *change_capability = (int *)&cdo->capability; /* hack */ + int rc; char vname[16]; cdinfo(CD_OPEN, "entering register_cdrom\n"); + if ((rc = check_cdrom_init()) != 0) + return rc; + if (major < 0 || major >= MAX_BLKDEV) return -1; if (cdo->open == NULL || cdo->release == NULL) @@ -2706,11 +2716,29 @@ #endif /* CONFIG_SYSCTL */ -static int __init cdrom_init(void) +static int check_cdrom_init(void) { - int n_entries = CDROM_MAX_CDROMS / (sizeof(unsigned long) * 8); + if (!initialized) + { + int n_entries; + + initialized = 1; + n_entries = CDROM_MAX_CDROMS / (sizeof(unsigned long) * 8); - cdrom_numbers = kmalloc(n_entries * sizeof(unsigned long), GFP_KERNEL); + cdrom_numbers = kmalloc(n_entries * sizeof(unsigned long), GFP_KERNEL); + + if (cdrom_numbers == NULL) + return -ENOMEM; + } + return 0; +} + +static int __init cdrom_init(void) +{ + int rc; + + if ((rc = check_cdrom_init()) != 0) + return rc; #ifdef CONFIG_SYSCTL cdrom_sysctl_register(); -- Dan Aloni dax@karrde.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/