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author | Alexey Dobriyan <adobriyan@gmail.com> | 2009-03-25 22:48:06 +0300 |
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committer | Alexey Dobriyan <adobriyan@gmail.com> | 2009-03-31 01:14:44 +0400 |
commit | 99b76233803beab302123d243eea9e41149804f3 (patch) | |
tree | 398178210fe66845ccd6fa4258ba762a87e023ad /arch/x86/kernel/cpu/mtrr/if.c | |
parent | 3dec7f59c370c7b58184d63293c3dc984d475840 (diff) | |
download | linux-99b76233803beab302123d243eea9e41149804f3.tar.bz2 |
proc 2/2: remove struct proc_dir_entry::owner
Setting ->owner as done currently (pde->owner = THIS_MODULE) is racy
as correctly noted at bug #12454. Someone can lookup entry with NULL
->owner, thus not pinning enything, and release it later resulting
in module refcount underflow.
We can keep ->owner and supply it at registration time like ->proc_fops
and ->data.
But this leaves ->owner as easy-manipulative field (just one C assignment)
and somebody will forget to unpin previous/pin current module when
switching ->owner. ->proc_fops is declared as "const" which should give
some thoughts.
->read_proc/->write_proc were just fixed to not require ->owner for
protection.
rmmod'ed directories will be empty and return "." and ".." -- no harm.
And directories with tricky enough readdir and lookup shouldn't be modular.
We definitely don't want such modular code.
Removing ->owner will also make PDE smaller.
So, let's nuke it.
Kudos to Jeff Layton for reminding about this, let's say, oversight.
http://bugzilla.kernel.org/show_bug.cgi?id=12454
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Diffstat (limited to 'arch/x86/kernel/cpu/mtrr/if.c')
-rw-r--r-- | arch/x86/kernel/cpu/mtrr/if.c | 10 |
1 files changed, 1 insertions, 9 deletions
diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c index 4c4214690dd1..fb73a52913a4 100644 --- a/arch/x86/kernel/cpu/mtrr/if.c +++ b/arch/x86/kernel/cpu/mtrr/if.c @@ -377,10 +377,6 @@ static const struct file_operations mtrr_fops = { .release = mtrr_close, }; - -static struct proc_dir_entry *proc_root_mtrr; - - static int mtrr_seq_show(struct seq_file *seq, void *offset) { char factor; @@ -423,11 +419,7 @@ static int __init mtrr_if_init(void) (!cpu_has(c, X86_FEATURE_CENTAUR_MCR))) return -ENODEV; - proc_root_mtrr = - proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_fops); - - if (proc_root_mtrr) - proc_root_mtrr->owner = THIS_MODULE; + proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_fops); return 0; } |