| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <4FBE16FC.4070009@parallels.com>
Date: Thu, 24 May 2012 15:09:48 +0400
From: Stanislav Kinsbursky <skinsbursky@...allels.com>
To: "J. Bruce Fields" <bfields@...ldses.org>
CC: "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devel@...nvz.org" <devel@...nvz.org>
Subject: Re: [PATCH] NFSd: fix locking in nfsd_forget_delegations()
On 24.05.2012 14:56, J. Bruce Fields wrote:
> On Thu, May 24, 2012 at 08:41:35AM +0400, Stanislav Kinsbursky wrote:
>> 24.05.2012 01:31, J. Bruce Fields написал:
>>> On Tue, May 22, 2012 at 02:25:14PM +0400, Stanislav Kinsbursky wrote:
>>>> This patch adds recall_lock hold to nfsd_forget_delegations() to protect
>>>> nfsd_process_n_delegations() call.
>>>> Also, looks like it would be better to collect delegations to some local
>>>> on-stack list, and then unhash collected list. This split allows to simplify
>>>> locking, because delegation traversing is protected by recall_lock, when
>>>> delegation unhash is protected by client_mutex.
>>> All this indirection is getting a little much.
>>>
>>> How about replacing nfsd_process_n_delegations by something that always
>>> does the list-move?:
>>
>> Is it correct?
>> List move is suitable for unhash delegations since we anyway remove
>> delegation from fi_delegations list.
>> But seems we don't do this for delegations recall...
>
> Oh, blah, you're right of course.
>
> Still, this seems a little tangled, and I'd prefer not to have to add
> the useless extra parameter to break_one_deleg().
>
Ok, I'll try to handle it somehow...
> --b.
>
>>
>>
>>> void nfsd_forget_delegations(u64 num)
>>> {
>>> unsigned int count;
>>> list_head victims;
>>>
>>> nfs4_lock_state();
>>> count = nfsd_get_n_delegations(num,&victims);
>>> list_for_each_entry_safe(...,&victims, ...)
>>> unhash_delegation();
>>> unlock_state();
>>> }
>>>
>>> ditto for recall_delegations, and take the recall_lock inside
>>> nfsd_get_n_delegations?
>>>
>>> Or something like that.
>>>
>>> --b.
>>>
>>>> Signed-off-by: Stanislav Kinsbursky<skinsbursky@...allels.com>
>>>> ---
>>>> fs/nfsd/nfs4state.c | 32 ++++++++++++++++++++++++--------
>>>> 1 files changed, 24 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>>> index 21266c7..f004e61 100644
>>>> --- a/fs/nfsd/nfs4state.c
>>>> +++ b/fs/nfsd/nfs4state.c
>>>> @@ -2597,7 +2597,7 @@ out:
>>>> return ret;
>>>> }
>>>>
>>>> -static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
>>>> +static void nfsd_break_one_deleg(struct nfs4_delegation *dp, void *data)
>>>> {
>>>> /* We're assuming the state code never drops its reference
>>>> * without first removing the lease. Since we're in this lease
>>>> @@ -2633,7 +2633,7 @@ static void nfsd_break_deleg_cb(struct file_lock *fl)
>>>> spin_lock(&recall_lock);
>>>> fp->fi_had_conflict = true;
>>>> list_for_each_entry(dp,&fp->fi_delegations, dl_perfile)
>>>> - nfsd_break_one_deleg(dp);
>>>> + nfsd_break_one_deleg(dp, NULL);
>>>> spin_unlock(&recall_lock);
>>>> }
>>>>
>>>> @@ -4694,7 +4694,7 @@ void nfsd_forget_openowners(u64 num)
>>>> printk(KERN_INFO "NFSD: Forgot %d open owners", count);
>>>> }
>>>>
>>>> -int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegation *))
>>>> +int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegation *, void *), void *data)
>>>> {
>>>> int i, count = 0;
>>>> struct nfs4_file *fp, *fnext;
>>>> @@ -4703,7 +4703,7 @@ int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegatio
>>>> for (i = 0; i< FILE_HASH_SIZE; i++) {
>>>> list_for_each_entry_safe(fp, fnext,&file_hashtbl[i], fi_hash) {
>>>> list_for_each_entry_safe(dp, dnext,&fp->fi_delegations, dl_perfile) {
>>>> - deleg_func(dp);
>>>> + deleg_func(dp, data);
>>>> if (++count == num)
>>>> return count;
>>>> }
>>>> @@ -4713,15 +4713,31 @@ int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegatio
>>>> return count;
>>>> }
>>>>
>>>> +/* Called under the recall_lock spinlock. */
>>>> +static void
>>>> +collect_delegation(struct nfs4_delegation *dp, void *data)
>>>> +{
>>>> + struct list_head *list = data;
>>>> +
>>>> + list_move(&dp->dl_perfile, list);
>>>> +}
>>>> +
>>>> void nfsd_forget_delegations(u64 num)
>>>> {
>>>> unsigned int count;
>>>> + struct nfs4_delegation *dp, *dnext;
>>>> + LIST_HEAD(unhash_list);
>>>>
>>>> - nfs4_lock_state();
>>>> - count = nfsd_process_n_delegations(num, unhash_delegation);
>>>> - nfs4_unlock_state();
>>>> + spin_lock(&recall_lock);
>>>> + count = nfsd_process_n_delegations(num, collect_delegation,&unhash_list);
>>>> + spin_unlock(&recall_lock);
>>>>
>>>> printk(KERN_INFO "NFSD: Forgot %d delegations", count);
>>>> +
>>>> + nfs4_lock_state();
>>>> + list_for_each_entry_safe(dp, dnext,&unhash_list, dl_perfile)
>>>> + unhash_delegation(dp);
>>>> + nfs4_unlock_state();
>>>> }
>>>>
>>>> void nfsd_recall_delegations(u64 num)
>>>> @@ -4730,7 +4746,7 @@ void nfsd_recall_delegations(u64 num)
>>>>
>>>> nfs4_lock_state();
>>>> spin_lock(&recall_lock);
>>>> - count = nfsd_process_n_delegations(num, nfsd_break_one_deleg);
>>>> + count = nfsd_process_n_delegations(num, nfsd_break_one_deleg, NULL);
>>>> spin_unlock(&recall_lock);
>>>> nfs4_unlock_state();
>>>>
>>>>
>>
--
Best regards,
Stanislav Kinsbursky
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists