From: Dawei Li <dawei.li@shingroup.cn>
To: Eric Dumazet <edumazet@google.com>
Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com,
ioana.ciornei@nxp.com, wintera@linux.ibm.com,
twinkler@linux.ibm.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: [PATCH net-next 1/2] net/iucv: Avoid explicit cpumask var allocation on stack
Date: Sat, 30 Mar 2024 13:07:06 +0800 [thread overview]
Message-ID: <4E49057A4198779C+Zged+hXhxE4GksiL@centos8> (raw)
In-Reply-To: <CANn89iJzuw8_ti4P4tJ_A3Fd0QCjHTBjasbm_J3N8up=gK8Aow@mail.gmail.com>
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);
> > }
>
WARNING: multiple messages have this Message-ID (diff)
From: Dawei Li <dawei.li@shingroup.cn>
To: Eric Dumazet <edumazet@google.com>
Cc: <davem@davemloft.net>, <kuba@kernel.org>, <pabeni@redhat.com>,
<ioana.ciornei@nxp.com>, <wintera@linux.ibm.com>,
<twinkler@linux.ibm.com>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-s390@vger.kernel.org>
Subject: Re: [PATCH net-next 1/2] net/iucv: Avoid explicit cpumask var allocation on stack
Date: Sat, 30 Mar 2024 13:07:06 +0800 [thread overview]
Message-ID: <4E49057A4198779C+Zged+hXhxE4GksiL@centos8> (raw)
Message-ID: <20240330050706.s_RIPrZB7UccQyc0yBgBPe4uM-ExUzcK_5K6tv_DzJI@z> (raw)
In-Reply-To: <CANn89iJzuw8_ti4P4tJ_A3Fd0QCjHTBjasbm_J3N8up=gK8Aow@mail.gmail.com>
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);
> > }
>
WARNING: multiple messages have this Message-ID (diff)
From: Dawei Li <dawei.li@shingroup.cn>
To: Eric Dumazet <edumazet@google.com>
Cc: <davem@davemloft.net>, <kuba@kernel.org>, <pabeni@redhat.com>,
<ioana.ciornei@nxp.com>, <wintera@linux.ibm.com>,
<twinkler@linux.ibm.com>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-s390@vger.kernel.org>
Subject: Re: [PATCH net-next 1/2] net/iucv: Avoid explicit cpumask var allocation on stack
Date: Sat, 30 Mar 2024 13:07:06 +0800 [thread overview]
Message-ID: <4E49057A4198779C+Zged+hXhxE4GksiL@centos8> (raw)
Message-ID: <20240330050706.qat0AxZwnCEDaJTfuI7B4QVSC0YMzKnlME7Q7Y9WNG0@z> (raw)
In-Reply-To: <CANn89iJzuw8_ti4P4tJ_A3Fd0QCjHTBjasbm_J3N8up=gK8Aow@mail.gmail.com>
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);
> > }
>
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Date: Sat, 30 Mar 2024 13:07:06 +0800
From: Dawei Li <dawei.li@shingroup.cn>
To: Eric Dumazet <edumazet@google.com>
CC: <davem@davemloft.net>, <kuba@kernel.org>, <pabeni@redhat.com>,
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Subject: Re: [PATCH net-next 1/2] net/iucv: Avoid explicit cpumask var
allocation on stack
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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);
> > }
>
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Date: Sat, 30 Mar 2024 13:07:06 +0800
From: Dawei Li <dawei.li@shingroup.cn>
To: Eric Dumazet <edumazet@google.com>
CC: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com,
ioana.ciornei@nxp.com, wintera@linux.ibm.com,
twinkler@linux.ibm.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: [PATCH net-next 1/2] net/iucv: Avoid explicit cpumask var
allocation on stack
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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);
> > }
>
next prev parent reply other threads:[~2024-03-30 5:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-29 10:56 [PATCH net-next 0/2] Avoid explicit cpumask var allocation on stack Dawei Li
2024-03-29 10:56 ` [PATCH net-next 1/2] net/iucv: " Dawei Li
2024-03-29 13:21 ` Eric Dumazet
2024-03-30 5:07 ` Dawei Li [this message]
2024-03-30 5:07 ` Dawei Li
2024-03-30 5:07 ` Dawei Li
2024-03-29 10:56 ` [PATCH net-next 2/2] net/dpaa2: " Dawei Li
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