Search Linux Wireless

Re: [PATCH net v2] net: wireless: marvell: mwifiex: fix sleep in atomic context bugs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 5/19/2022 5:08 PM, duoming@xxxxxxxxxx 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



[Index of Archives]     [Linux Host AP]     [ATH6KL]     [Linux Wireless Personal Area Network]     [Linux Bluetooth]     [Wireless Regulations]     [Linux Netdev]     [Kernel Newbies]     [Linux Kernel]     [IDE]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Hiking]     [MIPS Linux]     [ARM Linux]     [Linux RAID]

  Powered by Linux