Messages in this thread | | | From | "" <> | Subject | RE: [PATCH v5 04/21] x86/resctrl: Group struct rdt_hw_domain cleanup | Date | Fri, 1 Jul 2022 06:37:33 +0000 |
| |
Hi James
> On 29/06/2022 09:33, tan.shaopeng@fujitsu.com wrote: > >> domain_add_cpu() and domain_remove_cpu() need to kfree() the child > >> arrays that were allocated by domain_setup_ctrlval(). > >> > >> As this memory is moved around, and new arrays are created, adjusting > >> the error handling cleanup code becomes noisier. > >> > >> To simplify this, move all the kfree() calls into a domain_free() helper. > >> This depends on struct rdt_hw_domain being kzalloc()d, allowing it to > >> unconditionally kfree() all the child arrays. > > >> diff --git a/arch/x86/kernel/cpu/resctrl/core.c > >> b/arch/x86/kernel/cpu/resctrl/core.c > >> index 25f30148478b..e37889f7a1a5 100644 > >> --- a/arch/x86/kernel/cpu/resctrl/core.c > >> +++ b/arch/x86/kernel/cpu/resctrl/core.c > >> @@ -414,6 +414,13 @@ void setup_default_ctrlval(struct rdt_resource > >> *r, u32 *dc, u32 *dm) > >> } > >> } > >> > >> +static void domain_free(struct rdt_hw_domain *hw_dom) { > >> + kfree(hw_dom->ctrl_val); > >> + kfree(hw_dom->mbps_val); > >> + kfree(hw_dom); > >> +} > >> + > >> static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain > *d) { > >> struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); @@ -488,7 > >> +495,7 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r) > >> rdt_domain_reconfigure_cdp(r); > >> > >> if (r->alloc_capable && domain_setup_ctrlval(r, d)) { > >> - kfree(hw_dom); > >> + domain_free(hw_dom); > > > domain_free(hw_dom) is executed when fails allocated hw_dom->ctrl_val > > by kmalloc_array() in domain_setup_ctrlval(r, d), but hw_dom->ctrl_val > > is freed in domain_free(hw_dom). > > > > Also, hw_dom->mbps_val is not allocated at this time, but it is freed > > in domain_free(hw_dom). > > Yes, this is deliberate. These cases end up doing: > | kfree(NULL); > which is harmless. kfree() checks for a NULL argument and does nothing. > > The alternative would be to spread the cleanup all over the place, so it only calls > kfree() on something that has been allocated - this would be more complex and > easier to miss something.
Thank you for explaining. I learned.
Best regards, Shaopeng
| |