[v3] raw/ifpga: fix pthread cannot join
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Commit Message
From: Tianfei Zhang <tianfei.zhang@intel.com>
When we want to close a thread, we should set a flag to notify
thread handler function.
Fixes: 9c006c45 ("raw/ifpga: scan PCIe BDF device tree")
Cc: stable@dpdk.org
Signed-off-by: Tianfei Zhang <tianfei.zhang@intel.com>
---
v2: update commit log
---
v3: set thread id to 0 after pthread_join
---
drivers/raw/ifpga/ifpga_rawdev.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
Comments
On Thu, Jan 20, 2022 at 7:01 AM Wei Huang <wei.huang@intel.com> wrote:
>
> From: Tianfei Zhang <tianfei.zhang@intel.com>
>
> When we want to close a thread, we should set a flag to notify
> thread handler function.
>
> Fixes: 9c006c45 ("raw/ifpga: scan PCIe BDF device tree")
> Cc: stable@dpdk.org
>
> Signed-off-by: Tianfei Zhang <tianfei.zhang@intel.com>
> ---
> v2: update commit log
> ---
> v3: set thread id to 0 after pthread_join
Evaluating/setting a pthread_t variable is a bad idea: this type
should be considered opaque.
Plus here, the ifpga_monitor_start variable already indicates whether
ifpga_monitor_start_thread is valid.
Only checking for ifpga_monitor_start in ifpga_rawdev_gsd_handle loop
should be enough.
> ---
> drivers/raw/ifpga/ifpga_rawdev.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/raw/ifpga/ifpga_rawdev.c b/drivers/raw/ifpga/ifpga_rawdev.c
> index 8d9db58..2bc569b 100644
> --- a/drivers/raw/ifpga/ifpga_rawdev.c
> +++ b/drivers/raw/ifpga/ifpga_rawdev.c
> @@ -497,7 +497,7 @@ static int set_surprise_link_check_aer(
> int gsd_enable, ret;
> #define MS 1000
>
> - while (1) {
> + while (ifpga_monitor_start) {
> gsd_enable = 0;
> for (i = 0; i < IFPGA_RAWDEV_NUM; i++) {
> ifpga_rdev = &ifpga_rawdevices[i];
> @@ -542,18 +542,21 @@ static int set_surprise_link_check_aer(
> static int
> ifpga_monitor_stop_func(void)
> {
> + void *status;
This status variable is unused, no need for it.
> int ret;
>
> - if (ifpga_monitor_start == 1) {
> + if ((ifpga_monitor_start == 1) && ifpga_monitor_start_thread) {
> + ifpga_monitor_start = 0;
> +
> ret = pthread_cancel(ifpga_monitor_start_thread);
> if (ret)
> IFPGA_RAWDEV_PMD_ERR("Can't cancel the thread");
>
> - ret = pthread_join(ifpga_monitor_start_thread, NULL);
> + ret = pthread_join(ifpga_monitor_start_thread, &status);
> if (ret)
> IFPGA_RAWDEV_PMD_ERR("Can't join the thread");
>
> - ifpga_monitor_start = 0;
> + ifpga_monitor_start_thread = 0;
>
> return ret;
> }
> --
> 1.8.3.1
>
On Thu, 20 Jan 2022 00:58:14 -0500
Wei Huang <wei.huang@intel.com> wrote:
> diff --git a/drivers/raw/ifpga/ifpga_rawdev.c b/drivers/raw/ifpga/ifpga_rawdev.c
> index 8d9db58..2bc569b 100644
> --- a/drivers/raw/ifpga/ifpga_rawdev.c
> +++ b/drivers/raw/ifpga/ifpga_rawdev.c
> @@ -497,7 +497,7 @@ static int set_surprise_link_check_aer(
> int gsd_enable, ret;
> #define MS 1000
>
> - while (1) {
> + while (ifpga_monitor_start) {
This will work on x86 CPU but not on CPU's with weak memory
ordering like ARM.
You need to use atomic_builtin when accessing a flag shared between
threads that is not being protected by a lock.
> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Thursday, January 20, 2022 11:47 PM
> To: Huang, Wei <wei.huang@intel.com>
> Cc: dev@dpdk.org; Xu, Rosen <rosen.xu@intel.com>; Zhang, Qi Z
> <qi.z.zhang@intel.com>; stable@dpdk.org; Zhang, Tianfei
> <tianfei.zhang@intel.com>; Yigit, Ferruh <ferruh.yigit@intel.com>
> Subject: Re: [PATCH v3] raw/ifpga: fix pthread cannot join
>
> On Thu, 20 Jan 2022 00:58:14 -0500
> Wei Huang <wei.huang@intel.com> wrote:
>
> > diff --git a/drivers/raw/ifpga/ifpga_rawdev.c
> > b/drivers/raw/ifpga/ifpga_rawdev.c
> > index 8d9db58..2bc569b 100644
> > --- a/drivers/raw/ifpga/ifpga_rawdev.c
> > +++ b/drivers/raw/ifpga/ifpga_rawdev.c
> > @@ -497,7 +497,7 @@ static int set_surprise_link_check_aer(
> > int gsd_enable, ret;
> > #define MS 1000
> >
> > - while (1) {
> > + while (ifpga_monitor_start) {
>
> This will work on x86 CPU but not on CPU's with weak memory ordering like
> ARM.
>
> You need to use atomic_builtin when accessing a flag shared between threads
> that is not being protected by a lock.
We submitted a v5 patch for your suggestion, but got a " coding style issues" which said that:
Warning in drivers/raw/ifpga/ifpga_rawdev.c:
Using rte_atomicNN_xxx
We look at the devtools/checkpatches.sh script, it mentioned that rte_atomic APIs are forbidden.
ifpga_monitor_start just a flags to enable and disable the threads not share with threads. When the driver init it will start the thread,
when the driver remove it want to stop the thread. I don't think it will has a concurrency issue on this scenario.
@@ -497,7 +497,7 @@ static int set_surprise_link_check_aer(
int gsd_enable, ret;
#define MS 1000
- while (1) {
+ while (ifpga_monitor_start) {
gsd_enable = 0;
for (i = 0; i < IFPGA_RAWDEV_NUM; i++) {
ifpga_rdev = &ifpga_rawdevices[i];
@@ -542,18 +542,21 @@ static int set_surprise_link_check_aer(
static int
ifpga_monitor_stop_func(void)
{
+ void *status;
int ret;
- if (ifpga_monitor_start == 1) {
+ if ((ifpga_monitor_start == 1) && ifpga_monitor_start_thread) {
+ ifpga_monitor_start = 0;
+
ret = pthread_cancel(ifpga_monitor_start_thread);
if (ret)
IFPGA_RAWDEV_PMD_ERR("Can't cancel the thread");
- ret = pthread_join(ifpga_monitor_start_thread, NULL);
+ ret = pthread_join(ifpga_monitor_start_thread, &status);
if (ret)
IFPGA_RAWDEV_PMD_ERR("Can't join the thread");
- ifpga_monitor_start = 0;
+ ifpga_monitor_start_thread = 0;
return ret;
}