Messages in this thread | | | Date | Fri, 20 May 2022 09:08:52 -0700 | Subject | Re: [PATCH net v2] net: wireless: marvell: mwifiex: fix sleep in atomic context bugs | From | Jeff Johnson <> |
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On 5/19/2022 5:08 PM, duoming@zju.edu.cn wrote: > Hello, > > On Thu, 19 May 2022 08:48:44 -0700 Jeff Johnson wrote: > >>>>> There are sleep in atomic context bugs when uploading device dump >>>>> data on usb interface. The root cause is that the operations that >>>>> may sleep are called in fw_dump_timer_fn which is a timer handler. >>>>> The call tree shows the execution paths that could lead to bugs: >>>>> >>>>> (Interrupt context) >>>>> fw_dump_timer_fn >>>>> mwifiex_upload_device_dump >>>>> dev_coredumpv(..., GFP_KERNEL) >> >> just looking at this description, why isn't the simple fix just to >> change this call to use GFP_ATOMIC? > > Because change the parameter of dev_coredumpv() to GFP_ATOMIC could only solve > partial problem. The following GFP_KERNEL parameters are in /lib/kobject.c > which is not influenced by dev_coredumpv(). > > kobject_set_name_vargs > kvasprintf_const(GFP_KERNEL, ...); //may sleep > kstrdup(s, GFP_KERNEL); //may sleep
Then it seems there is a problem with dev_coredumpm().
dev_coredumpm() takes a gfp param which means it expects to be called in any context, but it then calls dev_set_name() which, as you point out, cannot be called from an atomic context.
So if we cannot change the fact that dev_set_name() cannot be called from an atomic context, then it would seem to follow that dev_coredumpv()/dev_coredumpm() also cannot be called from an atomic context and hence their gfp param is pointless and should presumably be removed.
/jeff
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