On Fri, May 24, 2019 at 03:47:34PM +0100, Jon Hunter wrote: > > On 24/05/2019 15:33, Gen Zhang wrote: > > On Fri, May 24, 2019 at 09:33:13AM +0100, Jon Hunter wrote: > >> > >> On 24/05/2019 01:50, Gen Zhang wrote: > >>> In tegra_wm9712_driver_probe(), 'machine->codec' is allocated by > >>> platform_device_alloc(). When it is NULL, function returns ENOMEM. > >>> However, 'machine' is allocated by devm_kzalloc() before this site. > >>> Thus we should free 'machine' before function ends to prevent memory > >>> leaking. > >> > >> Memory allocated by devm_xxx() is automatically freed on failure so this > >> is not correct. > > Thanks for your comments, Jon. But after I examined the code, I am still > > confused about the usage of devm_kmalloc(). You can kindly refer to > > hisi_sas_debugfs_init() in drivers/scsi/hisi_sas/hisi_sas_main.c. And > > devm_kfree() is used to free a memory allocated by devm_kmalloc(). And > > I found other situations similar to this in other files. > > > > So, I hope you can give me some guidance on this. Thanks! > > Please refer to the devres documentation [0]. > > Cheers, > Jon > > [0] https://www.kernel.org/doc/Documentation/driver-model/devres.txt > > -- > nvpublic Thanks for your reply. I figured out that devm_kmalloc will free the memory no matter fail or not. But I still want to ask why other codes as I above mentioned use devm_kfree() to free memory allocated by devm_kmalloc(). If the memory is automatically freed, is this devm_kfee() redundant codes that should be removed? Am I misunderstanding this again or it is something else? Thanks Gen
