Messages in this thread | | | Date | Tue, 17 Jan 2023 11:27:53 +0200 | Subject | Re: [PATCH net-next v2] net: ethernet: ti: am65-cpsw/cpts: Fix CPTS release action | From | Roger Quadros <> |
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Siddharth,
On 17/01/2023 07:00, Siddharth Vadapalli wrote: > 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(). >
Yes, I agree.
>> >>> 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.
Correct.
> > > 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.
Do you really need a separate am65_cpsw_cpts_cleanup() or can just add the NULL check in am65_cpts_release()?
cheers, -roger
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