From: "Li, Ming4" <ming4.li@intel.com>
To: Ira Weiny <ira.weiny@intel.com>, <dave@stgolabs.net>,
<jonathan.cameron@huawei.com>, <dave.jiang@intel.com>,
<alison.schofield@intel.com>, <vishal.l.verma@intel.com>,
<dan.j.williams@intel.com>
Cc: <linux-cxl@vger.kernel.org>
Subject: Re: [PATCH 1/3] cxl/port: Use __free() to drop put_device() for cxl_port
Date: Thu, 22 Aug 2024 09:26:52 +0800 [thread overview]
Message-ID: <8ac82c61-7871-4914-b376-32431868622c@intel.com> (raw)
In-Reply-To: <66c65e2917d00_1719d294ed@iweiny-mobl.notmuch>
On 8/22/2024 5:37 AM, Ira Weiny wrote:
> Li Ming wrote:
>> Using scope-based resource management __free() marco with a new helper
>> called put_cxl_port() to drop open coded the put_device() used to
>> dereference the 'struct device' of a cxl_port.
>>
>> Suggested-by: Dan Williams <dan.j.williams@intel.com>
>> Signed-off-by: Li Ming <ming4.li@intel.com>
>> ---
>> drivers/cxl/core/pci.c | 6 ++----
>> drivers/cxl/core/port.c | 25 +++++++++----------------
>> drivers/cxl/cxl.h | 2 ++
>> drivers/cxl/mem.c | 5 ++---
>> drivers/cxl/pci.c | 7 ++-----
>> 5 files changed, 17 insertions(+), 28 deletions(-)
>>
>> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
>> index 51132a575b27..4725e37d90fb 100644
>> --- a/drivers/cxl/core/pci.c
>> +++ b/drivers/cxl/core/pci.c
>> @@ -915,15 +915,13 @@ static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
>> struct pci_dev *pdev = to_pci_dev(cxlds->dev);
>> struct aer_capability_regs aer_regs;
>> struct cxl_dport *dport;
>> - struct cxl_port *port;
>> int severity;
>>
>> - port = cxl_pci_find_port(pdev, &dport);
>> + struct cxl_port *port __free(put_cxl_port) =
>> + cxl_pci_find_port(pdev, &dport);
>> if (!port)
>> return;
>>
>> - put_device(&port->dev);
> I don't think this is wrong but we are not holding the lock for the
> duration of the function where before we were not.
>
> It seems like this is somewhat an abuse of the cxl_pci_find_port() call in
> that we don't really need the cxl_port reference but rather the dport... :-/
Thank you for the review.
Yes, seems like that, but CXL core does not provide a helper function to find a dport via pci device without getting the cxl_port reference yet.
>> -
>> if (!cxl_rch_get_aer_info(dport->regs.dport_aer, &aer_regs))
>> return;
>>
>> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
>> index 1d5007e3795a..6119cb3ad25c 100644
>> --- a/drivers/cxl/core/port.c
>> +++ b/drivers/cxl/core/port.c
>> @@ -1472,7 +1472,7 @@ static void cxl_detach_ep(void *data)
>> struct cxl_memdev *cxlmd = data;
>>
>> for (int i = cxlmd->depth - 1; i >= 1; i--) {
>> - struct cxl_port *port, *parent_port;
>> + struct cxl_port *parent_port;
>> struct detach_ctx ctx = {
>> .cxlmd = cxlmd,
>> .depth = i,
>> @@ -1485,7 +1485,7 @@ static void cxl_detach_ep(void *data)
>> port_has_memdev);
>> if (!dev)
>> continue;
>> - port = to_cxl_port(dev);
>> + struct cxl_port *port __free(put_cxl_port) = to_cxl_port(dev);
> This threw me because 'to_cxl_port' does not take a reference...
>
> Seems ok though.
Yes, to_cxl_port() does not take a reference here, but the 'dev' is provided by a bus_find_device() which will take a reference for the 'dev'.
maybe I should use __free() for the 'dev' like below? I think it is clearer.
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 1d5007e3795a..e4bff611e8fa 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1481,8 +1481,8 @@ static void cxl_detach_ep(void *data)
struct cxl_ep *ep;
bool died = false;
- dev = bus_find_device(&cxl_bus_type, NULL, &ctx,
- port_has_memdev);
+ struct device *dev __free(put_device) = bus_find_device(&cxl_bus_type, NULL,
+ &ctx, port_has_memdev);
if (!dev)
continue;
port = to_cxl_port(dev);
@@ -1512,7 +1512,6 @@ static void cxl_detach_ep(void *data)
dev_name(&port->dev));
delete_switch_port(port);
}
- put_device(&port->dev);
device_unlock(&parent_port->dev);
}
}
>
>>
>> parent_port = to_cxl_port(port->dev.parent);
>> device_lock(&parent_port->dev);
>> @@ -1512,7 +1512,6 @@ static void cxl_detach_ep(void *data)
>> dev_name(&port->dev));
>> delete_switch_port(port);
>> }
>> - put_device(&port->dev);
>> device_unlock(&parent_port->dev);
>> }
>> }
>> @@ -1539,8 +1538,8 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
>> struct device *uport_dev,
>> struct device *dport_dev)
>> {
>> + struct cxl_port *port __free(put_cxl_port) = NULL;
>> struct device *dparent = grandparent(dport_dev);
>> - struct cxl_port *port, *parent_port = NULL;
>> struct cxl_dport *dport, *parent_dport;
>> resource_size_t component_reg_phys;
>> int rc;
>> @@ -1556,7 +1555,8 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
>> return -ENXIO;
>> }
>>
>> - parent_port = find_cxl_port(dparent, &parent_dport);
>> + struct cxl_port *parent_port __free(put_cxl_port) =
>> + find_cxl_port(dparent, &parent_dport);
>> if (!parent_port) {
>> /* iterate to create this parent_port */
>> return -EAGAIN;
>> @@ -1596,10 +1596,8 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
>> */
>> rc = -ENXIO;
>> }
>> - put_device(&port->dev);
>> }
>>
>> - put_device(&parent_port->dev);
>> return rc;
>> }
>>
>> @@ -1630,7 +1628,6 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
>> struct device *dport_dev = grandparent(iter);
>> struct device *uport_dev;
>> struct cxl_dport *dport;
>> - struct cxl_port *port;
>>
>> /*
>> * The terminal "grandparent" in PCI is NULL and @platform_bus
>> @@ -1649,7 +1646,8 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
>> dev_dbg(dev, "scan: iter: %s dport_dev: %s parent: %s\n",
>> dev_name(iter), dev_name(dport_dev),
>> dev_name(uport_dev));
>> - port = find_cxl_port(dport_dev, &dport);
>> + struct cxl_port *port __free(put_cxl_port) =
> Does __free() get called before the next iteration of the loop? I guess
> it does because it would be out of scope outside the loop?
>
> Ira
Yes, It will get called before the next iteration of the loop. I have validated it.
>
>> + find_cxl_port(dport_dev, &dport);
>> if (port) {
>> dev_dbg(&cxlmd->dev,
>> "found already registered port %s:%s\n",
>> @@ -1664,18 +1662,13 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
>> * the parent_port lock as the current port may be being
>> * reaped.
>> */
>> - if (rc && rc != -EBUSY) {
>> - put_device(&port->dev);
>> + if (rc && rc != -EBUSY)
>> return rc;
>> - }
>>
>> /* Any more ports to add between this one and the root? */
>> - if (!dev_is_cxl_root_child(&port->dev)) {
>> - put_device(&port->dev);
>> + if (!dev_is_cxl_root_child(&port->dev))
>> continue;
>> - }
>>
>> - put_device(&port->dev);
>> return 0;
>> }
>>
>> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
>> index 9afb407d438f..cad297fba700 100644
>> --- a/drivers/cxl/cxl.h
>> +++ b/drivers/cxl/cxl.h
>> @@ -744,6 +744,8 @@ struct cxl_root *find_cxl_root(struct cxl_port *port);
>> void put_cxl_root(struct cxl_root *cxl_root);
>> DEFINE_FREE(put_cxl_root, struct cxl_root *, if (_T) put_cxl_root(_T))
>>
>> +DEFINE_FREE(put_cxl_port, struct cxl_port *,
>> + if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev))
>> int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd);
>> void cxl_bus_rescan(void);
>> void cxl_bus_drain(void);
>> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
>> index 7de232eaeb17..ab9b8ab8df44 100644
>> --- a/drivers/cxl/mem.c
>> +++ b/drivers/cxl/mem.c
>> @@ -109,7 +109,6 @@ static int cxl_mem_probe(struct device *dev)
>> struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
>> struct cxl_dev_state *cxlds = cxlmd->cxlds;
>> struct device *endpoint_parent;
>> - struct cxl_port *parent_port;
>> struct cxl_dport *dport;
>> struct dentry *dentry;
>> int rc;
>> @@ -146,7 +145,8 @@ static int cxl_mem_probe(struct device *dev)
>> if (rc)
>> return rc;
>>
>> - parent_port = cxl_mem_find_port(cxlmd, &dport);
>> + struct cxl_port *parent_port __free(put_cxl_port) =
>> + cxl_mem_find_port(cxlmd, &dport);
>> if (!parent_port) {
>> dev_err(dev, "CXL port topology not found\n");
>> return -ENXIO;
>> @@ -179,7 +179,6 @@ static int cxl_mem_probe(struct device *dev)
>> rc = devm_cxl_add_endpoint(endpoint_parent, cxlmd, dport);
>> unlock:
>> device_unlock(endpoint_parent);
>> - put_device(&parent_port->dev);
>> if (rc)
>> return rc;
>>
>> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
>> index 4be35dc22202..26e75499abdd 100644
>> --- a/drivers/cxl/pci.c
>> +++ b/drivers/cxl/pci.c
>> @@ -473,7 +473,6 @@ static bool is_cxl_restricted(struct pci_dev *pdev)
>> static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
>> struct cxl_register_map *map)
>> {
>> - struct cxl_port *port;
>> struct cxl_dport *dport;
>> resource_size_t component_reg_phys;
>>
>> @@ -482,14 +481,12 @@ static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
>> .resource = CXL_RESOURCE_NONE,
>> };
>>
>> - port = cxl_pci_find_port(pdev, &dport);
>> + struct cxl_port *port __free(put_cxl_port) =
>> + cxl_pci_find_port(pdev, &dport);
>> if (!port)
>> return -EPROBE_DEFER;
>>
>> component_reg_phys = cxl_rcd_component_reg_phys(&pdev->dev, dport);
>> -
>> - put_device(&port->dev);
>> -
>> if (component_reg_phys == CXL_RESOURCE_NONE)
>> return -ENXIO;
>>
>> --
>> 2.40.1
>>
>
prev parent reply other threads:[~2024-08-22 1:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-13 7:05 [PATCH 1/3] cxl/port: Use __free() to drop put_device() for cxl_port Li Ming
2024-08-13 7:05 ` [PATCH 2/3] cxl/port: Use scoped_guard() to drop device_lock()/unlock pair Li Ming
2024-08-21 21:49 ` Ira Weiny
2024-08-22 1:47 ` Li, Ming4
2024-08-13 7:05 ` [PATCH 3/3] cxl/port: Refactor __devm_cxl_add_port() to drop goto pattern Li Ming
2024-08-21 22:01 ` Ira Weiny
2024-08-22 2:07 ` Li, Ming4
2024-08-21 21:37 ` [PATCH 1/3] cxl/port: Use __free() to drop put_device() for cxl_port Ira Weiny
2024-08-22 1:26 ` Li, Ming4 [this message]
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