The patch titled
i82875p_edac: fix module remove
has been added to the -mm tree. Its filename is
i82875p_edac-fix-module-remove.patch
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Subject: i82875p_edac: fix module remove
From: Jarkko Lavinen <jlavi@xxxxxx>
Fix module removal bugs of i82875p_edac. Also i82975x_edac code seems to
have the same module removal bugs as in i82875p_edac.
The problems were:
1. In module removal i82875p_remove_one() is never called.
Variable i82875p_registered is newer changed from 1, which
guarantees i82875p_remove_one() is not called (and even if it were
called, it would be called in wrong order).
As a result, the edac_mc workque is not stopped and keeps probing.
If kernel debugging options are not enabled, user may not notice
anything going wrong.
if debugging options are enabled and I do "rmmod i82875p_edac", I
get:
edac debug: edac_pci_workq_function() checking
BUG: unable to handle kernel paging request at f882d16f
...
call trace:
[<f8834df3>] ? edac_mc_workq_function+0x55/0x7e [edac_core]
[<c0233974>] ? run_workqueue+0xd7/0x1a5
[<c023392f>] ? run_workqueue+0x92/0x1a5
[<f8834d9e>] ? edac_mc_workq_function+0x0/0x7e [edac_core]
[<c0233af9>] ? worker_thread+0xb7/0xc3
[<c0236a7b>] ? autoremove_wake_function+0x0/0x33
[<c0233a42>] ? worker_thread+0x0/0xc3
[<c0236809>] ? kthread+0x3b/0x61
[<c02367ce>] ? kthread+0x0/0x61
[<c0204587>] ? kernel_thread_helper+0x7/0x10
Fix for this is to get rid of needles variable i82875p_registered
altogether and run i82875p_remove_one() *before*
pci_unregister_driver().
2. edac_mc_del_mc() uses mci after freeing mci
edac_mc_del_mc() calls calls edac_remove_sysfs_mci_device(). The
kobject refcount of mci drops to 0 and mci is freed. After this
mci is accessed via debug print and i82875p_remove_one() still
uses mci->pvt and tries to free mci again with edac_mc_free().
The fix for this is add kobject_get(&mci->edac_mci_kobj) after
edac_mc_alloc(). Then the mci is still available after returning
from edac_mc_del_mc() with refcount 1, and mci->pvt is still
available. When i82875p_remove_one() finally calls edac_mc_free(),
this will cause kobject_put() and mci is released properly.
Signed-off-by: Jarkko Lavinen <jlavi@xxxxxx>
Cc: Doug Thompson <norsk5@xxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/edac/i82875p_edac.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff -puN drivers/edac/i82875p_edac.c~i82875p_edac-fix-module-remove drivers/edac/i82875p_edac.c
--- a/drivers/edac/i82875p_edac.c~i82875p_edac-fix-module-remove
+++ a/drivers/edac/i82875p_edac.c
@@ -182,8 +182,6 @@ static struct pci_dev *mci_pdev; /* init
* already registered driver
*/
-static int i82875p_registered = 1;
-
static struct edac_pci_ctl_info *i82875p_pci;
static void i82875p_get_error_info(struct mem_ctl_info *mci,
@@ -410,6 +408,9 @@ static int i82875p_probe1(struct pci_dev
goto fail0;
}
+ /* Keeps mci available after edac_mc_del_mc() till edac_mc_free() */
+ kobject_get(&mci->edac_mci_kobj);
+
debugf3("%s(): init mci\n", __func__);
mci->dev = &pdev->dev;
mci->mtype_cap = MEM_FLAG_DDR;
@@ -452,6 +453,7 @@ static int i82875p_probe1(struct pci_dev
return 0;
fail1:
+ kobject_put(&mci->edac_mci_kobj);
edac_mc_free(mci);
fail0:
@@ -579,12 +581,11 @@ static void __exit i82875p_exit(void)
{
debugf3("%s()\n", __func__);
+ i82875p_remove_one(mci_pdev);
+ pci_dev_put(mci_pdev);
+
pci_unregister_driver(&i82875p_driver);
- if (!i82875p_registered) {
- i82875p_remove_one(mci_pdev);
- pci_dev_put(mci_pdev);
- }
}
module_init(i82875p_init);
_
Patches currently in -mm which might be from jlavi@xxxxxx are
i82875p_edac-fix-overflow-device-resource-setup.patch
i82875p_edac-fix-module-remove.patch
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