| Message ID | 20240329105610.922675-2-dawei.li@shingroup.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Avoid explicit cpumask var allocation on stack | expand |
On Fri, Mar 29, 2024 at 11:57 AM Dawei Li <dawei.li@shingroup.cn> wrote: > > For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask > variable on stack is not recommended since it can cause potential stack > overflow. > > Instead, kernel code should always use *cpumask_var API(s) to allocate > cpumask var in config-neutral way, leaving allocation strategy to > CONFIG_CPUMASK_OFFSTACK. > > Use *cpumask_var API(s) to address it. > > Signed-off-by: Dawei Li <dawei.li@shingroup.cn> > --- > net/iucv/iucv.c | 37 ++++++++++++++++++++++++++----------- > 1 file changed, 26 insertions(+), 11 deletions(-) > > diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c > index a4ab615ca3e3..b51f46ec32f9 100644 > --- a/net/iucv/iucv.c > +++ b/net/iucv/iucv.c > @@ -520,14 +520,19 @@ static void iucv_setmask_mp(void) > */ > static void iucv_setmask_up(void) > { > - cpumask_t cpumask; > + cpumask_var_t cpumask; > int cpu; > > + if (!alloc_cpumask_var(&cpumask, GFP_KERNEL)) > + return; This can not be right. iucv_setmask_up() is not supposed to fail. Since iucv_setmask_up() is only called with iucv_register_mutex held, you could simply add a 'static' for @cpumask variable. > + > /* Disable all cpu but the first in cpu_irq_cpumask. */ > - cpumask_copy(&cpumask, &iucv_irq_cpumask); > - cpumask_clear_cpu(cpumask_first(&iucv_irq_cpumask), &cpumask); > - for_each_cpu(cpu, &cpumask) > + cpumask_copy(cpumask, &iucv_irq_cpumask); > + cpumask_clear_cpu(cpumask_first(&iucv_irq_cpumask), cpumask); > + for_each_cpu(cpu, cpumask) > smp_call_function_single(cpu, iucv_block_cpu, NULL, 1); > + > + free_cpumask_var(cpumask); > }
Hi Eric, On Fri, Mar 29, 2024 at 02:21:28PM +0100, Eric Dumazet wrote: > On Fri, Mar 29, 2024 at 11:57 AM Dawei Li <dawei.li@shingroup.cn> wrote: > > > > For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask > > variable on stack is not recommended since it can cause potential stack > > overflow. > > > > Instead, kernel code should always use *cpumask_var API(s) to allocate > > cpumask var in config-neutral way, leaving allocation strategy to > > CONFIG_CPUMASK_OFFSTACK. > > > > Use *cpumask_var API(s) to address it. > > > > Signed-off-by: Dawei Li <dawei.li@shingroup.cn> > > --- > > net/iucv/iucv.c | 37 ++++++++++++++++++++++++++----------- > > 1 file changed, 26 insertions(+), 11 deletions(-) > > > > diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c > > index a4ab615ca3e3..b51f46ec32f9 100644 > > --- a/net/iucv/iucv.c > > +++ b/net/iucv/iucv.c > > @@ -520,14 +520,19 @@ static void iucv_setmask_mp(void) > > */ > > static void iucv_setmask_up(void) > > { > > - cpumask_t cpumask; > > + cpumask_var_t cpumask; > > int cpu; > > > > + if (!alloc_cpumask_var(&cpumask, GFP_KERNEL)) > > + return; > > This can not be right. iucv_setmask_up() is not supposed to fail. > > Since iucv_setmask_up() is only called with iucv_register_mutex held, > you could simply add a 'static' for @cpumask variable. Correct, iucv_register_mutex is a global lock and can serialize access on static cpumask var. I will respin V2 as you suggested. Thanks, Dawei > > > > > + > > /* Disable all cpu but the first in cpu_irq_cpumask. */ > > - cpumask_copy(&cpumask, &iucv_irq_cpumask); > > - cpumask_clear_cpu(cpumask_first(&iucv_irq_cpumask), &cpumask); > > - for_each_cpu(cpu, &cpumask) > > + cpumask_copy(cpumask, &iucv_irq_cpumask); > > + cpumask_clear_cpu(cpumask_first(&iucv_irq_cpumask), cpumask); > > + for_each_cpu(cpu, cpumask) > > smp_call_function_single(cpu, iucv_block_cpu, NULL, 1); > > + > > + free_cpumask_var(cpumask); > > } >
diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c index a4ab615ca3e3..b51f46ec32f9 100644 --- a/net/iucv/iucv.c +++ b/net/iucv/iucv.c @@ -520,14 +520,19 @@ static void iucv_setmask_mp(void) */ static void iucv_setmask_up(void) { - cpumask_t cpumask; + cpumask_var_t cpumask; int cpu; + if (!alloc_cpumask_var(&cpumask, GFP_KERNEL)) + return; + /* Disable all cpu but the first in cpu_irq_cpumask. */ - cpumask_copy(&cpumask, &iucv_irq_cpumask); - cpumask_clear_cpu(cpumask_first(&iucv_irq_cpumask), &cpumask); - for_each_cpu(cpu, &cpumask) + cpumask_copy(cpumask, &iucv_irq_cpumask); + cpumask_clear_cpu(cpumask_first(&iucv_irq_cpumask), cpumask); + for_each_cpu(cpu, cpumask) smp_call_function_single(cpu, iucv_block_cpu, NULL, 1); + + free_cpumask_var(cpumask); } /* @@ -628,23 +633,33 @@ static int iucv_cpu_online(unsigned int cpu) static int iucv_cpu_down_prep(unsigned int cpu) { - cpumask_t cpumask; + cpumask_var_t cpumask; + int ret = 0; if (!iucv_path_table) return 0; - cpumask_copy(&cpumask, &iucv_buffer_cpumask); - cpumask_clear_cpu(cpu, &cpumask); - if (cpumask_empty(&cpumask)) + if (!alloc_cpumask_var(&cpumask, GFP_KERNEL)) + return -ENOMEM; + + cpumask_copy(cpumask, &iucv_buffer_cpumask); + cpumask_clear_cpu(cpu, cpumask); + if (cpumask_empty(cpumask)) { /* Can't offline last IUCV enabled cpu. */ - return -EINVAL; + ret = -EINVAL; + goto __free_cpumask; + } iucv_retrieve_cpu(NULL); if (!cpumask_empty(&iucv_irq_cpumask)) - return 0; + goto __free_cpumask; + smp_call_function_single(cpumask_first(&iucv_buffer_cpumask), iucv_allow_cpu, NULL, 1); - return 0; + +__free_cpumask: + free_cpumask_var(cpumask); + return ret; } /**
For CONFIG_CPUMASK_OFFSTACK=y kernel, explicit allocation of cpumask variable on stack is not recommended since it can cause potential stack overflow. Instead, kernel code should always use *cpumask_var API(s) to allocate cpumask var in config-neutral way, leaving allocation strategy to CONFIG_CPUMASK_OFFSTACK. Use *cpumask_var API(s) to address it. Signed-off-by: Dawei Li <dawei.li@shingroup.cn> --- net/iucv/iucv.c | 37 ++++++++++++++++++++++++++----------- 1 file changed, 26 insertions(+), 11 deletions(-)