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staging: dgnc: cleanup properly

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dgnc_cleanup_module() was called when the module unloaded to do a total
cleanup and it was also called if pci_register_driver() fails. But
dgnc_cleanup_module() will try dgnc_remove_driver_sysfiles() but the
sysfiles will be created only if pci_register_driver() succeeds.
So if pci_register_driver() fails and we try dgnc_cleanup_module() then we
were getting:

[  942.001479] BUG: unable to handle kernel NULL pointer dereference at 00000018
[  942.001482] IP: [<c122c7a8>] sysfs_remove_file_ns+0x8/0x20

with part of the call trace as:

[  942.001544] Call Trace:
[  942.001555]  [<c149acc6>] driver_remove_file+0x16/0x20
[  942.001571]  [<f864a708>] dgnc_remove_driver_sysfiles+0x18/0x40 [dgnc]
[  942.001575]  [<f8643ac7>] dgnc_cleanup_module+0x47/0x260 [dgnc]
[  942.001577]  [<f86cb000>] ? 0xf86cb000
[  942.001580]  [<f86cb1e6>] dgnc_init_module+0x1e6/0x1000 [dgnc]

Lets have a separate cleanup function which will execute
dgnc_remove_driver_sysfiles() depending on the argument passed to it.

Reported-by: Navy Cheng <navych@126.com>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sudip Mukherjee 2016-02-27 17:33:35 +05:30 committed by Greg Kroah-Hartman
parent b3ca2e08e7
commit 18f038e6bf
1 changed files with 13 additions and 8 deletions
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21
drivers/staging/dgnc/dgnc_driver.c
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@ -125,12 +125,7 @@ static struct pci_driver dgnc_driver = {
*
************************************************************************/
/*
* dgnc_cleanup_module()
*
* Module unload. This is where it all ends.
*/
static void dgnc_cleanup_module(void)
static void cleanup(bool sysfiles)
{
int i;
unsigned long flags;
@ -142,7 +137,8 @@ static void dgnc_cleanup_module(void)
/* Turn off poller right away. */
del_timer_sync(&dgnc_poll_timer);
dgnc_remove_driver_sysfiles(&dgnc_driver);
if (sysfiles)
dgnc_remove_driver_sysfiles(&dgnc_driver);
device_destroy(dgnc_class, MKDEV(dgnc_Major, 0));
class_destroy(dgnc_class);
@ -155,7 +151,16 @@ static void dgnc_cleanup_module(void)
}
dgnc_tty_post_uninit();
}
/*
* dgnc_cleanup_module()
*
* Module unload. This is where it all ends.
*/
static void dgnc_cleanup_module(void)
{
cleanup(true);
pci_unregister_driver(&dgnc_driver);
}
@ -182,7 +187,7 @@ static int __init dgnc_init_module(void)
rc = pci_register_driver(&dgnc_driver);
if (rc) {
pr_warn("WARNING: dgnc driver load failed. No Digi Neo or Classic boards found.\n");
dgnc_cleanup_module();
cleanup(false);
return rc;
}
dgnc_create_driver_sysfiles(&dgnc_driver);