Documentation/power/freezing-of-tasks.rst

7 I. What is the freezing of tasks?
10 The freezing of tasks is a mechanism by which user space processes and some
28 indicate whether the system is to undergo a freezing operation. And
72 has initiated a freezing operation, the freezing of tasks will fail and the
83 Rationale behind the functions dealing with freezing and thawing of tasks
91     kernel threads without freezing userspace tasks
115 Generally speaking, there is a couple of reasons to use the freezing of tasks:
137    freezing them earlier. [Of course, this also means that device drivers
144    example, be troublesome and without the freezing of tasks we would need some
147 Although Linus Torvalds doesn't like the freezing of tasks, he said this in one
161 freezing user threads I don't find really objectionable."
171 4. Another reason for freezing tasks is to prevent user space processes from
176    is quite difficult to achieve without the freezing of tasks.  Consider,
182 V. Are there any problems related to the freezing of tasks?
187 First of all, the freezing of kernel threads may be tricky if they depend one
193 Second, there are the following two problems related to the freezing of user
208 There are also problems that the freezing of tasks tends to expose, although
212 at this point.  So, seemingly, the failure is due to the freezing of tasks.
215 request_firmware() will fail regardless of whether or not the freezing of tasks
216 is used.  Consequently, the problem is not really related to the freezing of
224 VI. Are there any precautions to be taken to prevent freezing failures?
237 mutex_[un]lock(&system_transition_mutex) since that could lead to freezing
242 freezing failure.
245 since they ask the freezer to skip freezing this task, since it is anyway
249 mutex_[un]lock(&system_transition_mutex). That would prevent freezing failures.