Messages in this thread | | | Date | Wed, 18 Jan 2023 10:28:10 +0530 | Subject | Re: [PATCH net-next v2] net: ethernet: ti: am65-cpsw/cpts: Fix CPTS release action | From | Siddharth Vadapalli <> |
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On 17/01/23 17:04, Leon Romanovsky wrote: > On Tue, Jan 17, 2023 at 10:30:26AM +0530, 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; >> } > > This code block is unreachable, because of config earlier. > 1916 static int am65_cpsw_init_cpts(struct am65_cpsw_common *common) > 1917 { > ... > 1923 if (!IS_ENABLED(CONFIG_TI_K3_AM65_CPTS)) > 1924 return 0; > ... > 1933 cpts = am65_cpts_create(dev, reg_base, node); > 1934 if (IS_ERR(cpts)) { > 1935 int ret = PTR_ERR(cpts); > 1936 > 1937 of_node_put(node); > 1938 if (ret == -EOPNOTSUPP) { > 1939 dev_info(dev, "cpts disabled\n"); > 1940 return 0; > 1941 } > > You should delete all the logic above.
Leon,
I did not realize that the code block is unreachable. I had assumed it was valid and handled the case where the CONFIG_TI_K3_AM65_CPTS config is enabled and one of the functions within am65_cpts_create() return -EOPNOTSUPP, since this section of code was already present. I analyzed the possible return values of all the functions within am65_cpts_create() and like you pointed out, none of them seem to return -EOPNOTSUPP.
Roger,
Please let me know if you can identify a case where CONFIG_TI_K3_AM65_CPTS is enabled and one of the functions within the am65_cpts_create() function return -EOPNOTSUPP. I was unable to find one after analyzing the return values. Therefore, I shall proceed with adding a cleanup patch which deletes the unreachable code block, followed by updating this patch with Leon's first suggestion of dropping am65_cpsw_cpts_cleanup() entirely, since common->cpts being NULL won't have any problem and am65_cpts_release() can be invoked directly. I will post these two patches as the v3 series if there are no issues.
Regards, Siddharth.
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