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-Wunused-const-variable in drivers/usb/host/xhci-tegra.c #533

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nhukc opened this issue Jun 12, 2019 · 3 comments
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-Wunused-const-variable in drivers/usb/host/xhci-tegra.c #533

nhukc opened this issue Jun 12, 2019 · 3 comments
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@nhukc
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-Wunused-const-variable [ARCH] arm64 This bug impacts ARCH=arm64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.3 This bug was fixed in Linux 5.3

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@nhukc
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nhukc commented Jun 12, 2019 

drivers/usb/host/xhci-tegra.c:357:27: warning: unused variable 'mbox_cmd_name' [-Wunused-const-variable]
static const char * const mbox_cmd_name[] = {
                          ^

Each entry of the array holds a string value that matches with command request enums. I would guess that this was intended for logging and was never implemented.
@nhukc nhukc added [BUG] linux A bug that should be fixed in the mainline kernel. [ARCH] arm64 This bug impacts ARCH=arm64 low priority This bug is not critical and not a priority -Wunused-const-variable labels Jun 12, 2019
@nhukc nhukc self-assigned this Jun 12, 2019
@nhukc
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nhukc commented Jun 13, 2019

Reached out to author+maintainers: https://groups.google.com/forum/#!topic/clang-built-linux/Jh6Y6k0bR_Q

@nhukc
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nhukc commented Jun 13, 2019

Patch submitted: https://groups.google.com/forum/#!topic/clang-built-linux/Jh6Y6k0bR_Q

@nhukc nhukc added the [PATCH] Submitted A patch has been submitted for review label Jun 13, 2019
fengguang pushed a commit to 0day-ci/linux that referenced this issue Jun 14, 2019
@nhukc @intel-lab-lkp
usb: host: xhci-tegra: Fix Wunused-const-variable
1293209 
Clang produces the following warning

drivers/usb/host/xhci-tegra.c:357:27: warning: unused variable
'mbox_cmd_name' [-Wunused-const-variable]
static const char * const mbox_cmd_name[] = {

Looks like it was intended for logging or debugging, but was
never implemented. Removing mbox_cmd_name.

Cc: clang-built-linux@googlegroups.com
Link: ClangBuiltLinux#533
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
fengguang pushed a commit to 0day-ci/linux that referenced this issue Jun 18, 2019
@nhukc @gregkh
usb: host: xhci-tegra: Fix Wunused-const-variable
1a65a03 
Clang produces the following warning

drivers/usb/host/xhci-tegra.c:357:27: warning: unused variable
'mbox_cmd_name' [-Wunused-const-variable]
static const char * const mbox_cmd_name[] = {

Looks like it was intended for logging or debugging, but was
never implemented. Removing mbox_cmd_name.

Cc: clang-built-linux@googlegroups.com
Link: ClangBuiltLinux#533
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
@nhukc nhukc added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Jun 18, 2019
@nickdesaulniers
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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1a65a03561198f38f8198650b52f55a21cbb4b6c

@nickdesaulniers nickdesaulniers added [FIXED][LINUX] 5.3 This bug was fixed in Linux 5.3 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Jul 21, 2019
@tpimh tpimh removed the low priority This bug is not critical and not a priority label Sep 28, 2019
nathanchance pushed a commit that referenced this issue Sep 11, 2020
@osctobe @broonie
regulator: push allocation in regulator_init_coupling() outside of lock
73a3212 
Allocating memory with regulator_list_mutex held makes lockdep unhappy
when memory pressure makes the system do fs_reclaim on eg. eMMC using
a regulator. Push the lock inside regulator_init_coupling() after the
allocation.

======================================================
WARNING: possible circular locking dependency detected
5.7.13+ #533 Not tainted
------------------------------------------------------
kswapd0/383 is trying to acquire lock:
cca78ca4 (&sbi->write_io[i][j].io_rwsem){++++}-{3:3}, at: __submit_merged_write_cond+0x104/0x154
but task is already holding lock:
c0e38518 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x50
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (fs_reclaim){+.+.}-{0:0}:
       fs_reclaim_acquire.part.11+0x40/0x50
       fs_reclaim_acquire+0x24/0x28
       __kmalloc+0x54/0x218
       regulator_register+0x860/0x1584
       dummy_regulator_probe+0x60/0xa8
[...]
other info that might help us debug this:

Chain exists of:
  &sbi->write_io[i][j].io_rwsem --> regulator_list_mutex --> fs_reclaim

Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(regulator_list_mutex);
                               lock(fs_reclaim);
  lock(&sbi->write_io[i][j].io_rwsem);
 *** DEADLOCK ***

1 lock held by kswapd0/383:
 #0: c0e38518 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x50
[...]

Fixes: d8ca7d1 ("regulator: core: Introduce API for regulators coupling customization")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1a889cf7f61c6429c9e6b34ddcdde99be77a26b6.1597195321.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown <broonie@kernel.org>
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-Wunused-const-variable [ARCH] arm64 This bug impacts ARCH=arm64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.3 This bug was fixed in Linux 5.3
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