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linux/drivers/android
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Carlos Llamas 08853ea15d binder: fix hang of unregistered readers 
commit 31643d84b8 upstream.

With the introduction of binder_available_for_proc_work_ilocked() in
commit 1b77e9dcc3 ("ANDROID: binder: remove proc waitqueue") a binder
thread can only "wait_for_proc_work" after its thread->looper has been
marked as BINDER_LOOPER_STATE_{ENTERED|REGISTERED}.

This means an unregistered reader risks waiting indefinitely for work
since it never gets added to the proc->waiting_threads. If there are no
further references to its waitqueue either the task will hang. The same
applies to readers using the (e)poll interface.

I couldn't find the rationale behind this restriction. So this patch
restores the previous behavior of allowing unregistered threads to
"wait_for_proc_work". Note that an error message for this scenario,
which had previously become unreachable, is now re-enabled.

Fixes: 1b77e9dcc3 ("ANDROID: binder: remove proc waitqueue")
Cc: stable@vger.kernel.org
Cc: Martijn Coenen <maco@google.com>
Cc: Arve Hjønnevåg <arve@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20240711201452.2017543-1-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-08-19 05:45:16 +02:00
..
binder.c binder: fix hang of unregistered readers 2024-08-19 05:45:16 +02:00
binder_alloc.c binder: fix race between mmput() and do_exit() 2024-01-25 14:52:46 -08:00
binder_alloc.h binder: fix memory leak in binder_init() 2023-08-16 18:21:59 +02:00
binder_alloc_selftest.c Revert "android: binder: stop saving a pointer to the VMA" 2023-06-05 09:21:24 +02:00
binder_internal.h binder: fix max_thread type inconsistency 2024-05-25 16:20:18 +02:00
binder_trace.h binder: add trace at free transaction. 2020-11-11 08:20:44 +01:00
binderfs.c binder: fix redefinition of seq_file attributes 2022-08-17 14:23:50 +02:00
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00