lkml.org 
[lkml]   [2017]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 4/9] staging: fsl-mc: don't use devres api for refcounted objects
Date


On 02/03/2017 02:02 AM, Stuart Yoder wrote:
>
>
>> -----Original Message-----
>> From: laurentiu.tudor@nxp.com [mailto:laurentiu.tudor@nxp.com]
>> Sent: Wednesday, February 01, 2017 5:43 AM
>> To: gregkh@linuxfoundation.org
>> Cc: devel@driverdev.osuosl.org; linux-kernel@vger.kernel.org; agraf@suse.de; arnd@arndb.de; Ioana
>> Ciornei <ioana.ciornei@nxp.com>; Ruxandra Ioana Radulescu <ruxandra.radulescu@nxp.com>; Bharat Bhushan
>> <bharat.bhushan@nxp.com>; Stuart Yoder <stuart.yoder@nxp.com>; Catalin Horghidan
>> <catalin.horghidan@nxp.com>; Leo Li <leoyang.li@nxp.com>; Roy Pledge <roy.pledge@nxp.com>; Laurentiu
>> Tudor <laurentiu.tudor@nxp.com>
>> Subject: [PATCH 4/9] staging: fsl-mc: don't use devres api for refcounted objects
>>
>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
>>
>> Mixing two memory management systems, in this case
>> managed device resource api and refcounted objects
>> is a bad idea. Lifetime of an object is controlled
>> by its refcount so allocating it with other apis
>> that have their own lifetime control is not ok.
>> Drop devm_*() apis in favor of plain allocations.
>>
>> While at it, let's drop the slab cache for objects
>> until we actually have proof that it improves
>> performance. This allows for some code cleanup.
>
> Those 2 changes (dropping devm_* apis and slab cache
> changes) are 2 orthogonal things, right? It would
> be better to split those into separate patches. Mixing
> them makes it harder to review.
>
>> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
>> ---
>> drivers/staging/fsl-mc/bus/fsl-mc-bus.c | 43 +++++----------------------------
>> 1 file changed, 6 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/staging/fsl-mc/bus/fsl-mc-bus.c b/drivers/staging/fsl-mc/bus/fsl-mc-bus.c
>> index 6601bde..c493427 100644
>> --- a/drivers/staging/fsl-mc/bus/fsl-mc-bus.c
>> +++ b/drivers/staging/fsl-mc/bus/fsl-mc-bus.c
>> @@ -27,8 +27,6 @@
>> #include "fsl-mc-private.h"
>> #include "dprc-cmd.h"
>>
>> -static struct kmem_cache *mc_dev_cache;
>> -
>> /**
>> * Default DMA mask for devices on a fsl-mc bus
>> */
>> @@ -422,17 +420,12 @@ bool fsl_mc_is_root_dprc(struct device *dev)
>> static void fsl_mc_device_release(struct device *dev)
>> {
>> struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
>> - struct fsl_mc_bus *mc_bus = NULL;
>>
>> kfree(mc_dev->regions);
>> -
>> - if (strcmp(mc_dev->obj_desc.type, "dprc") == 0)
>> - mc_bus = to_fsl_mc_bus(mc_dev);
>> -
>> - if (mc_bus)
>> - devm_kfree(mc_dev->dev.parent, mc_bus);
>> + if (!strcmp(mc_dev->obj_desc.type, "dprc"))
>> + kfree(to_fsl_mc_bus(mc_dev));
>> else
>> - kmem_cache_free(mc_dev_cache, mc_dev);
>> + kfree(mc_dev);
>> }
>>
>> /**
>> @@ -457,7 +450,7 @@ int fsl_mc_device_add(struct dprc_obj_desc *obj_desc,
>> /*
>> * Allocate an MC bus device object:
>> */
>> - mc_bus = devm_kzalloc(parent_dev, sizeof(*mc_bus), GFP_KERNEL);
>> + mc_bus = kzalloc(sizeof(*mc_bus), GFP_KERNEL);
>> if (!mc_bus)
>> return -ENOMEM;
>>
>> @@ -466,7 +459,7 @@ int fsl_mc_device_add(struct dprc_obj_desc *obj_desc,
>> /*
>> * Allocate a regular fsl_mc_device object:
>> */
>> - mc_dev = kmem_cache_zalloc(mc_dev_cache, GFP_KERNEL);
>> + mc_dev = kzalloc(sizeof(*mc_dev), GFP_KERNEL);
>> if (!mc_dev)
>> return -ENOMEM;
>> }
>> @@ -561,10 +554,7 @@ int fsl_mc_device_add(struct dprc_obj_desc *obj_desc,
>>
>> error_cleanup_dev:
>> kfree(mc_dev->regions);
>> - if (mc_bus)
>> - devm_kfree(parent_dev, mc_bus);
>> - else
>> - kmem_cache_free(mc_dev_cache, mc_dev);
>> + kfree(mc_bus ? (void *)mc_bus : (void *)mc_dev);
>>
>> return error;
>> }
>> @@ -578,23 +568,11 @@ int fsl_mc_device_add(struct dprc_obj_desc *obj_desc,
>> */
>> void fsl_mc_device_remove(struct fsl_mc_device *mc_dev)
>> {
>> - struct fsl_mc_bus *mc_bus = NULL;
>> -
>> - kfree(mc_dev->regions);
>> -
>> /*
>> * The device-specific remove callback will get invoked by device_del()
>> */
>> device_del(&mc_dev->dev);
>> put_device(&mc_dev->dev);
>> -
>> - if (strcmp(mc_dev->obj_desc.type, "dprc") == 0)
>> - mc_bus = to_fsl_mc_bus(mc_dev);
>> -
>> - if (mc_bus)
>> - devm_kfree(mc_dev->dev.parent, mc_bus);
>> - else
>> - kmem_cache_free(mc_dev_cache, mc_dev);
>> }
>
> The above changes in fsl_mc_device_remove(), I think
> actually belong in patch #3 of this series.
>

Agree. I think I end up doing a double free here.

---
Thanks & Best Regards, Laurentiu
\
 
 \ /
  Last update: 2017-02-03 11:32    [W:0.051 / U:1.796 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site