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Message-ID: <48CF78A9.9080907@de.ibm.com>
Date: Tue, 16 Sep 2008 11:13:13 +0200
From: Thomas Klein <osstklei@...ibm.com>
To: Sebastien Dugue <sebastien.dugue@...l.net>
CC: jeff@...zik.org, tklein@...ibm.com, tinytim@...ibm.com,
themann@...ibm.com, netdev@...r.kernel.org, hering2@...ibm.com,
linux-kernel@...r.kernel.org, jean-pierre.dion@...l.net,
linuxppc-dev@...abs.org, raisch@...ibm.com,
gilles.carry@....bull.net
Subject: Re: [PATCH 2/2] ehea: fix mutex and spinlock use
Sebastien Dugue wrote:
> On Mon, 15 Sep 2008 17:18:27 +0200 Thomas Klein <osstklei@...ibm.com> wrote:
>
>> NACK!
>>
>> I regret but this patch is wrong. It is not sufficient to only lock
>> the replacement of an old list with a new list. Building up those
>> lists is a 3-step process:
>>
>> 1. Count the number of entries a list will contain and allocate mem
>> 2. Fill the list
>> 3. Replace old list with updated list
>>
>> It's obvious that the contents of the list may not change during this
>> procedure. That means that not only the list build-up procedure must
>> be locked. It must be assured that no function that modifies the list's
>> content can be called while another list update is in progress.
>>
>> Jeff, please revert this patch.
>
> OK, your call, you know the code better than I do.
>
> But the locking could at least be pushed into ehea_update_firmware_handles()
> and ehea_update_bcmc_registrations() instead of being at each call site.
>
> Thanks,
>
> Sebastien.
>
It unfortunately can't. As I already mentioned "it must be assured that no
function that modifies the list's content can be called while another list
update is in progress". This means that for example ehea_broadcast_reg_helper()
may not run during a list update. That's why the locks surround these function
calls as well.
Thomas
>> Thanks
>> Thomas
>>
>>
>>
>> Sebastien Dugue wrote:
>>> Looks like to me that the ehea_fw_handles.lock mutex and the
>>> ehea_bcmc_regs.lock spinlock are taken much longer than necessary and could
>>> as well be pushed inside the functions that need them
>>> (ehea_update_firmware_handles() and ehea_update_bcmc_registrations())
>>> rather than at each callsite.
>>>
>>> Signed-off-by: Sebastien Dugue <sebastien.dugue@...l.net>
>>> ---
>>> drivers/net/ehea/ehea_main.c | 26 ++++----------------------
>>> 1 files changed, 4 insertions(+), 22 deletions(-)
>>>
>>> diff --git a/drivers/net/ehea/ehea_main.c b/drivers/net/ehea/ehea_main.c
>>> index b70c531..c765ec6 100644
>>> --- a/drivers/net/ehea/ehea_main.c
>>> +++ b/drivers/net/ehea/ehea_main.c
>>> @@ -219,9 +219,11 @@ static void ehea_update_firmware_handles(void)
>>> }
>>>
>>> out_update:
>>> + mutex_lock(&ehea_fw_handles.lock);
>>> kfree(ehea_fw_handles.arr);
>>> ehea_fw_handles.arr = arr;
>>> ehea_fw_handles.num_entries = i;
>>> + mutex_unlock(&ehea_fw_handles.lock);
>>> }
>>>
>>> static void ehea_update_bcmc_registrations(void)
>>> @@ -293,9 +295,11 @@ static void ehea_update_bcmc_registrations(void)
>>> }
>>>
>>> out_update:
>>> + spin_lock(&ehea_bcmc_regs.lock);
>>> kfree(ehea_bcmc_regs.arr);
>>> ehea_bcmc_regs.arr = arr;
>>> ehea_bcmc_regs.num_entries = i;
>>> + spin_unlock(&ehea_bcmc_regs.lock);
>>> }
>>>
>>> static struct net_device_stats *ehea_get_stats(struct net_device *dev)
>>> @@ -1770,8 +1774,6 @@ static int ehea_set_mac_addr(struct net_device *dev, void *sa)
>>>
>>> memcpy(dev->dev_addr, mac_addr->sa_data, dev->addr_len);
>>>
>>> - spin_lock(&ehea_bcmc_regs.lock);
>>> -
>>> /* Deregister old MAC in pHYP */
>>> if (port->state == EHEA_PORT_UP) {
>>> ret = ehea_broadcast_reg_helper(port, H_DEREG_BCMC);
>>> @@ -1792,7 +1794,6 @@ static int ehea_set_mac_addr(struct net_device *dev, void *sa)
>>>
>>> out_upregs:
>>> ehea_update_bcmc_registrations();
>>> - spin_unlock(&ehea_bcmc_regs.lock);
>>> out_free:
>>> kfree(cb0);
>>> out:
>>> @@ -1954,8 +1955,6 @@ static void ehea_set_multicast_list(struct net_device *dev)
>>> }
>>> ehea_promiscuous(dev, 0);
>>>
>>> - spin_lock(&ehea_bcmc_regs.lock);
>>> -
>>> if (dev->flags & IFF_ALLMULTI) {
>>> ehea_allmulti(dev, 1);
>>> goto out;
>>> @@ -1985,7 +1984,6 @@ static void ehea_set_multicast_list(struct net_device *dev)
>>> }
>>> out:
>>> ehea_update_bcmc_registrations();
>>> - spin_unlock(&ehea_bcmc_regs.lock);
>>> return;
>>> }
>>>
>>> @@ -2466,8 +2464,6 @@ static int ehea_up(struct net_device *dev)
>>> if (port->state == EHEA_PORT_UP)
>>> return 0;
>>>
>>> - mutex_lock(&ehea_fw_handles.lock);
>>> -
>>> ret = ehea_port_res_setup(port, port->num_def_qps,
>>> port->num_add_tx_qps);
>>> if (ret) {
>>> @@ -2504,8 +2500,6 @@ static int ehea_up(struct net_device *dev)
>>> }
>>> }
>>>
>>> - spin_lock(&ehea_bcmc_regs.lock);
>>> -
>>> ret = ehea_broadcast_reg_helper(port, H_REG_BCMC);
>>> if (ret) {
>>> ret = -EIO;
>>> @@ -2527,10 +2521,8 @@ out:
>>> ehea_info("Failed starting %s. ret=%i", dev->name, ret);
>>>
>>> ehea_update_bcmc_registrations();
>>> - spin_unlock(&ehea_bcmc_regs.lock);
>>>
>>> ehea_update_firmware_handles();
>>> - mutex_unlock(&ehea_fw_handles.lock);
>>>
>>> return ret;
>>> }
>>> @@ -2580,9 +2572,6 @@ static int ehea_down(struct net_device *dev)
>>> if (port->state == EHEA_PORT_DOWN)
>>> return 0;
>>>
>>> - mutex_lock(&ehea_fw_handles.lock);
>>> -
>>> - spin_lock(&ehea_bcmc_regs.lock);
>>> ehea_drop_multicast_list(dev);
>>> ehea_broadcast_reg_helper(port, H_DEREG_BCMC);
>>>
>>> @@ -2591,7 +2580,6 @@ static int ehea_down(struct net_device *dev)
>>> port->state = EHEA_PORT_DOWN;
>>>
>>> ehea_update_bcmc_registrations();
>>> - spin_unlock(&ehea_bcmc_regs.lock);
>>>
>>> ret = ehea_clean_all_portres(port);
>>> if (ret)
>>> @@ -2599,7 +2587,6 @@ static int ehea_down(struct net_device *dev)
>>> dev->name, ret);
>>>
>>> ehea_update_firmware_handles();
>>> - mutex_unlock(&ehea_fw_handles.lock);
>>>
>>> return ret;
>>> }
>>> @@ -3378,7 +3365,6 @@ static int __devinit ehea_probe_adapter(struct of_device *dev,
>>> ehea_error("Invalid ibmebus device probed");
>>> return -EINVAL;
>>> }
>>> - mutex_lock(&ehea_fw_handles.lock);
>>>
>>> adapter = kzalloc(sizeof(*adapter), GFP_KERNEL);
>>> if (!adapter) {
>>> @@ -3462,7 +3448,6 @@ out_free_ad:
>>>
>>> out:
>>> ehea_update_firmware_handles();
>>> - mutex_unlock(&ehea_fw_handles.lock);
>>> return ret;
>>> }
>>>
>>> @@ -3481,8 +3466,6 @@ static int __devexit ehea_remove(struct of_device *dev)
>>>
>>> flush_scheduled_work();
>>>
>>> - mutex_lock(&ehea_fw_handles.lock);
>>> -
>>> ibmebus_free_irq(adapter->neq->attr.ist1, adapter);
>>> tasklet_kill(&adapter->neq_tasklet);
>>>
>>> @@ -3492,7 +3475,6 @@ static int __devexit ehea_remove(struct of_device *dev)
>>> kfree(adapter);
>>>
>>> ehea_update_firmware_handles();
>>> - mutex_unlock(&ehea_fw_handles.lock);
>>>
>>> return 0;
>>> }
>>
>> _______________________________________________
>> Linuxppc-dev mailing list
>> Linuxppc-dev@...abs.org
>> https://ozlabs.org/mailman/listinfo/linuxppc-dev
>>
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