Messages in this thread | | | Date | Tue, 17 Jan 2023 10:30:26 +0530 | Subject | Re: [PATCH net-next v2] net: ethernet: ti: am65-cpsw/cpts: Fix CPTS release action | From | Siddharth Vadapalli <> |
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Roger, Leon,
On 16/01/23 21:31, Roger Quadros wrote: > Hi Siddharth, > > On 16/01/2023 09:43, Siddharth Vadapalli wrote: >> >> >> On 16/01/23 13:00, Leon Romanovsky wrote: >>> On Mon, Jan 16, 2023 at 10:15:17AM +0530, Siddharth Vadapalli wrote: >>>> The am65_cpts_release() function is registered as a devm_action in the >>>> am65_cpts_create() function in am65-cpts driver. When the am65-cpsw driver >>>> invokes am65_cpts_create(), am65_cpts_release() is added in the set of devm >>>> actions associated with the am65-cpsw driver's device. >>>> >>>> In the event of probe failure or probe deferral, the platform_drv_probe() >>>> function invokes dev_pm_domain_detach() which powers off the CPSW and the >>>> CPSW's CPTS hardware, both of which share the same power domain. Since the >>>> am65_cpts_disable() function invoked by the am65_cpts_release() function >>>> attempts to reset the CPTS hardware by writing to its registers, the CPTS >>>> hardware is assumed to be powered on at this point. However, the hardware >>>> is powered off before the devm actions are executed. >>>> >>>> Fix this by getting rid of the devm action for am65_cpts_release() and >>>> invoking it directly on the cleanup and exit paths. >>>> >>>> Fixes: f6bd59526ca5 ("net: ethernet: ti: introduce am654 common platform time sync driver") >>>> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com> >>>> Reviewed-by: Roger Quadros <rogerq@kernel.org> >>>> --- >>>> Changes from v1: >>>> 1. Fix the build issue when "CONFIG_TI_K3_AM65_CPTS" is not set. This >>>> error was reported by kernel test robot <lkp@intel.com> at: >>>> https://lore.kernel.org/r/202301142105.lt733Lt3-lkp@intel.com/ >>>> 2. Collect Reviewed-by tag from Roger Quadros. >>>> >>>> v1: >>>> https://lore.kernel.org/r/20230113104816.132815-1-s-vadapalli@ti.com/ >>>> >>>> drivers/net/ethernet/ti/am65-cpsw-nuss.c | 8 ++++++++ >>>> drivers/net/ethernet/ti/am65-cpts.c | 15 +++++---------- >>>> drivers/net/ethernet/ti/am65-cpts.h | 5 +++++ >>>> 3 files changed, 18 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c >>>> index 5cac98284184..00f25d8a026b 100644 >>>> --- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c >>>> +++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c >>>> @@ -1913,6 +1913,12 @@ static int am65_cpsw_am654_get_efuse_macid(struct device_node *of_node, >>>> return 0; >>>> } >>>> >>>> +static void am65_cpsw_cpts_cleanup(struct am65_cpsw_common *common) >>>> +{ >>>> + if (IS_ENABLED(CONFIG_TI_K3_AM65_CPTS) && common->cpts) >>> >>> Why do you have IS_ENABLED(CONFIG_TI_K3_AM65_CPTS), if >>> am65_cpts_release() defined as empty when CONFIG_TI_K3_AM65_CPTS not set? >>> >>> How is it possible to have common->cpts == NULL? >> >> Thank you for reviewing the patch. I realize now that checking >> CONFIG_TI_K3_AM65_CPTS is unnecessary. >> >> common->cpts remains NULL in the following cases:
I realized that the cases I mentioned are not explained clearly. Therefore, I will mention the cases again, along with the section of code they correspond to, in order to make it clear.
Case-1: am65_cpsw_init_cpts() returns 0 since CONFIG_TI_K3_AM65_CPTS is not enabled. This corresponds to the following section within am65_cpsw_init_cpts():
if (!IS_ENABLED(CONFIG_TI_K3_AM65_CPTS)) return 0;
In this case, common->cpts remains NULL, but it is not a problem even if the am65_cpsw_nuss_probe() fails later, since the am65_cpts_release() function is NOP. Thus, this case is not an issue.
Case-2: am65_cpsw_init_cpts() returns -ENOENT since the cpts node is not present in the device tree. This corresponds to the following section within am65_cpsw_init_cpts():
node = of_get_child_by_name(dev->of_node, "cpts"); if (!node) { dev_err(dev, "%s cpts not found\n", __func__); return -ENOENT; }
In this case as well, common->cpts remains NULL, but it is not a problem because the probe fails and the execution jumps to "err_of_clear", which doesn't invoke am65_cpsw_cpts_cleanup(). Therefore, common->cpts being NULL is not a problem.
Case-3 and Case-4 are described later in this mail.
>> 1. am65_cpsw_init_cpts() returns 0 since CONFIG_TI_K3_AM65_CPTS is not enabled. >> 2. am65_cpsw_init_cpts() returns -ENOENT since the cpts node is not defined. >> 3. The call to am65_cpts_create() fails within the am65_cpsw_init_cpts() >> function with a return value of 0 when cpts is disabled. > > In this case common->cpts is not NULL and is set to error pointer. > Probe will continue normally. > Is it OK to call any of the cpts APIs with invalid handle? > Also am65_cpts_release() will be called with invalid handle.
Yes Roger, thank you for pointing it out. When I wrote "cpts is disabled", I had meant that the following section is executed within the am65_cpsw_init_cpts() function:
Case-3:
cpts = am65_cpts_create(dev, reg_base, node); if (IS_ERR(cpts)) { int ret = PTR_ERR(cpts);
of_node_put(node); if (ret == -EOPNOTSUPP) { dev_info(dev, "cpts disabled\n"); return 0; }
...... }
Leon,
In the above code, when the section corresponding to: dev_info(dev, "cpts disabled\n");
is executed, CONFIG_TI_K3_AM65_CPTS is enabled. Therefore, the am65_cpts_release() is not NOP. If the probe fails after the call to am65_cpsw_init_cpts(), then the am65_cpsw_cpts_cleanup() function will be called in the cleanup path of probe, which needs to check for common->cpts not being NULL. This is because common->cpts is NULL after returning 0 from the am65_cpsw_init_cpts() function at the dev_info(dev, "cpts disabled\n");
section. Thus, I believe that in this case, am65_cpts_release() shouldn't be invoked from the am65_cpsw_cpts_cleanup() function, since it would have already been invoked from am65_cpts_create()'s cleanup path. This can be ensured by checking whether common->cpts is NULL or not, before invoking am65_cpts_release() within am65_cpsw_cpts_cleanup().
> >> 4. The call to am65_cpts_create() within the am65_cpsw_init_cpts() function >> fails with an error. > > In this case common->cpts is not NULL and will invoke am65_cpts_release() with > invalid handle.
Case-4: The call to am65_cpts_create() within the am65_cpsw_init_cpts() function fails with an error. This corresponds to the following section within am65_cpsw_init_cpts():
cpts = am65_cpts_create(dev, reg_base, node); if (IS_ERR(cpts)) { ...... dev_err(dev, "cpts create err %d\n", ret); return ret; }
Roger,
If the call to am65_cpts_create() fails with an error other than -EOPNOTSUPP, which corresponds to Case-4, the call to am65_cpts_release() would have been invoked within the am65_cpts_create()'s cleanup path itself if necessary. Also, when the error is not -EOPNOTSUPP, the am65_cpsw_init_cpts() function returns an error, due to which the execution jumps to "err_of_clear" in am65_cpsw_nuss_probe(). Therefore, am65_cpsw_cpts_cleanup() is not invoked in this case, due to which common->cpts being NULL is not a problem.
Roger, Leon, please review my comments and let me know. I think that Case-3 demands checking whether common->cpts is NULL or not, within the am65_cpsw_cpts_cleanup() function.
Regards, Siddharth.
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