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Remove always true condition in msgs #85

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merged 1 commit into from
Aug 15, 2018

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cujomalainey
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Clang was catching that since the char buffer was part of the struct
this will always result in true.

This will actually check the buffer's contents for the condition

@plbossart
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plbossart commented Aug 15, 2018

Ah yes, I saw this warning yesterday in the report from Dan Carpenter and couldn't figure out what it meant:
Old smatch warnings:
sound/soc/sof/topology.c:1417 sof_widget_ready() warn: this array is probably non-NULL. 'tw->sname'

Now I know!

Would you mind just doing a quick edit to make checkpath.pl happy and I'll merge asap.

WARNING: line over 80 characters
#21: FILE: sound/soc/sof/topology.c:1349:
+		strnlen(tw->sname, SNDRV_CTL_ELEM_ID_NAME_MAXLEN) > 0 ? tw->sname : "none");

WARNING: line over 80 characters
#30: FILE: sound/soc/sof/topology.c:1422:
+			strnlen(tw->sname, SNDRV_CTL_ELEM_ID_NAME_MAXLEN) > 0 ? tw->sname : "none", reply.rhdr.error);

Clang was catching that since the char buffer was part of the struct
this will always result in true.

Change-Id: Ice25db4baa16ac2cf2118ba1efaa4af89081bc80
Signed-off-by: Curtis Malainey <cujomalainey@google.com>
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cujomalainey commented Aug 15, 2018

I think the post commit hook keeps adding the change-id back in, I don't think there is any way around it unfortunately

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Thanks Curtis. Don't worry about the commit ID, I'll remove it when I squash the patch in topic/sof-dev-rebase

@plbossart plbossart merged commit 5420b87 into thesofproject:topic/sof-dev Aug 15, 2018
plbossart pushed a commit that referenced this pull request Sep 3, 2019
This patch fixes an issue that the following error is
possible to happen when ohci hardware causes an interruption
and the system is shutting down at the same time.

[   34.851754] usb 2-1: USB disconnect, device number 2
[   35.166658] irq 156: nobody cared (try booting with the "irqpoll" option)
[   35.173445] CPU: 0 PID: 22 Comm: kworker/0:1 Not tainted 5.3.0-rc5 #85
[   35.179964] Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
[   35.187886] Workqueue: usb_hub_wq hub_event
[   35.192063] Call trace:
[   35.194509]  dump_backtrace+0x0/0x150
[   35.198165]  show_stack+0x14/0x20
[   35.201475]  dump_stack+0xa0/0xc4
[   35.204785]  __report_bad_irq+0x34/0xe8
[   35.208614]  note_interrupt+0x2cc/0x318
[   35.212446]  handle_irq_event_percpu+0x5c/0x88
[   35.216883]  handle_irq_event+0x48/0x78
[   35.220712]  handle_fasteoi_irq+0xb4/0x188
[   35.224802]  generic_handle_irq+0x24/0x38
[   35.228804]  __handle_domain_irq+0x5c/0xb0
[   35.232893]  gic_handle_irq+0x58/0xa8
[   35.236548]  el1_irq+0xb8/0x180
[   35.239681]  __do_softirq+0x94/0x23c
[   35.243253]  irq_exit+0xd0/0xd8
[   35.246387]  __handle_domain_irq+0x60/0xb0
[   35.250475]  gic_handle_irq+0x58/0xa8
[   35.254130]  el1_irq+0xb8/0x180
[   35.257268]  kernfs_find_ns+0x5c/0x120
[   35.261010]  kernfs_find_and_get_ns+0x3c/0x60
[   35.265361]  sysfs_unmerge_group+0x20/0x68
[   35.269454]  dpm_sysfs_remove+0x2c/0x68
[   35.273284]  device_del+0x80/0x370
[   35.276683]  hid_destroy_device+0x28/0x60
[   35.280686]  usbhid_disconnect+0x4c/0x80
[   35.284602]  usb_unbind_interface+0x6c/0x268
[   35.288867]  device_release_driver_internal+0xe4/0x1b0
[   35.293998]  device_release_driver+0x14/0x20
[   35.298261]  bus_remove_device+0x110/0x128
[   35.302350]  device_del+0x148/0x370
[   35.305832]  usb_disable_device+0x8c/0x1d0
[   35.309921]  usb_disconnect+0xc8/0x2d0
[   35.313663]  hub_event+0x6e0/0x1128
[   35.317146]  process_one_work+0x1e0/0x320
[   35.321148]  worker_thread+0x40/0x450
[   35.324805]  kthread+0x124/0x128
[   35.328027]  ret_from_fork+0x10/0x18
[   35.331594] handlers:
[   35.333862] [<0000000079300c1d>] usb_hcd_irq
[   35.338126] [<0000000079300c1d>] usb_hcd_irq
[   35.342389] Disabling IRQ #156

ohci_shutdown() disables all the interrupt and rh_state is set to
OHCI_RH_HALTED. In other hand, ohci_irq() is possible to enable
OHCI_INTR_SF and OHCI_INTR_MIE on ohci_irq(). Note that OHCI_INTR_SF
is possible to be set by start_ed_unlink() which is called:
 ohci_irq()
  -> process_done_list()
   -> takeback_td()
    -> start_ed_unlink()

So, ohci_irq() has the following condition, the issue happens by
&ohci->regs->intrenable = OHCI_INTR_MIE | OHCI_INTR_SF and
ohci->rh_state = OHCI_RH_HALTED:

	/* interrupt for some other device? */
	if (ints == 0 || unlikely(ohci->rh_state == OHCI_RH_HALTED))
		return IRQ_NOTMINE;

To fix the issue, ohci_shutdown() holds the spin lock while disabling
the interruption and changing the rh_state flag to prevent reenable
the OHCI_INTR_MIE unexpectedly. Note that io_watchdog_func() also
calls the ohci_shutdown() and it already held the spin lock, so that
the patch makes a new function as _ohci_shutdown().

This patch is inspired by a Renesas R-Car Gen3 BSP patch
from Tho Vu.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/1566877910-6020-1-git-send-email-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bardliao pushed a commit to bardliao/linux that referenced this pull request Feb 25, 2020
The commit 54e53b2
  ("tty: serial: 8250: pass IRQ shared flag to UART ports")
nicely explained the problem:

---8<---8<---

On some systems IRQ lines between multiple UARTs might be shared. If so, the
irqflags have to be configured accordingly. The reason is: The 8250 port startup
code performs IRQ tests *before* the IRQ handler for that particular port is
registered. This is performed in serial8250_do_startup(). This function checks
whether IRQF_SHARED is configured and only then disables the IRQ line while
testing.

This test is performed upon each open() of the UART device. Imagine two UARTs
share the same IRQ line: On is already opened and the IRQ is active. When the
second UART is opened, the IRQ line has to be disabled while performing IRQ
tests. Otherwise an IRQ might handler might be invoked, but the IRQ itself
cannot be handled, because the corresponding handler isn't registered,
yet. That's because the 8250 code uses a chain-handler and invokes the
corresponding port's IRQ handling routines himself.

Unfortunately this IRQF_SHARED flag isn't configured for UARTs probed via device
tree even if the IRQs are shared. This way, the actual and shared IRQ line isn't
disabled while performing tests and the kernel correctly detects a spurious
IRQ. So, adding this flag to the DT probe solves the issue.

Note: The UPF_SHARE_IRQ flag is configured unconditionally. Therefore, the
IRQF_SHARED flag can be set unconditionally as well.

Example stack trace by performing `echo 1 > /dev/ttyS2` on a non-patched system:

|irq 85: nobody cared (try booting with the "irqpoll" option)
| [...]
|handlers:
|[<ffff0000080fc628>] irq_default_primary_handler threaded [<ffff00000855fbb8>] serial8250_interrupt
|Disabling IRQ thesofproject#85

---8<---8<---

But unfortunately didn't fix the root cause. Let's try again here by moving
IRQ flag assignment from serial_link_irq_chain() to serial8250_do_startup().

This should fix the similar issue reported for 8250_pnp case.

Since this change we don't need to have custom solutions in 8250_aspeed_vuart
and 8250_of drivers, thus, drop them.

Fixes: 1c2f049 ("serial: 8250: add IRQ trigger support")
Reported-by: Li RongQing <lirongqing@baidu.com>
Cc: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20200211135559.85960-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
paulstelian97 pushed a commit to paulstelian97/linux that referenced this pull request May 4, 2020
tools: labs: kernel_modules: fix dyndbg
aiChaoSONG pushed a commit to aiChaoSONG/linux that referenced this pull request May 6, 2021
…obes

Migrate to the new stack probes option
vijendarmukunda pushed a commit to vijendarmukunda/linux that referenced this pull request Feb 13, 2024
When I was testing mongodb over bcachefs with compression,
there is a lockdep warning when snapshotting mongodb data volume.

$ cat test.sh
prog=bcachefs

$prog subvolume create /mnt/data
$prog subvolume create /mnt/data/snapshots

while true;do
    $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s)
    sleep 1s
done

$ cat /etc/mongodb.conf
systemLog:
  destination: file
  logAppend: true
  path: /mnt/data/mongod.log

storage:
  dbPath: /mnt/data/

lockdep reports:
[ 3437.452330] ======================================================
[ 3437.452750] WARNING: possible circular locking dependency detected
[ 3437.453168] 6.7.0-rc7-custom+ thesofproject#85 Tainted: G            E
[ 3437.453562] ------------------------------------------------------
[ 3437.453981] bcachefs/35533 is trying to acquire lock:
[ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190
[ 3437.454875]
               but task is already holding lock:
[ 3437.455268] ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]
[ 3437.456009]
               which lock already depends on the new lock.

[ 3437.456553]
               the existing dependency chain (in reverse order) is:
[ 3437.457054]
               -> thesofproject#3 (&type->s_umount_key#48){.+.+}-{3:3}:
[ 3437.457507]        down_read+0x3e/0x170
[ 3437.457772]        bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]
[ 3437.458206]        __x64_sys_ioctl+0x93/0xd0
[ 3437.458498]        do_syscall_64+0x42/0xf0
[ 3437.458779]        entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ 3437.459155]
               -> thesofproject#2 (&c->snapshot_create_lock){++++}-{3:3}:
[ 3437.459615]        down_read+0x3e/0x170
[ 3437.459878]        bch2_truncate+0x82/0x110 [bcachefs]
[ 3437.460276]        bchfs_truncate+0x254/0x3c0 [bcachefs]
[ 3437.460686]        notify_change+0x1f1/0x4a0
[ 3437.461283]        do_truncate+0x7f/0xd0
[ 3437.461555]        path_openat+0xa57/0xce0
[ 3437.461836]        do_filp_open+0xb4/0x160
[ 3437.462116]        do_sys_openat2+0x91/0xc0
[ 3437.462402]        __x64_sys_openat+0x53/0xa0
[ 3437.462701]        do_syscall_64+0x42/0xf0
[ 3437.462982]        entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ 3437.463359]
               -> thesofproject#1 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}:
[ 3437.463843]        down_write+0x3b/0xc0
[ 3437.464223]        bch2_write_iter+0x5b/0xcc0 [bcachefs]
[ 3437.464493]        vfs_write+0x21b/0x4c0
[ 3437.464653]        ksys_write+0x69/0xf0
[ 3437.464839]        do_syscall_64+0x42/0xf0
[ 3437.465009]        entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ 3437.465231]
               -> #0 (sb_writers#10){.+.+}-{0:0}:
[ 3437.465471]        __lock_acquire+0x1455/0x21b0
[ 3437.465656]        lock_acquire+0xc6/0x2b0
[ 3437.465822]        mnt_want_write+0x46/0x1a0
[ 3437.465996]        filename_create+0x62/0x190
[ 3437.466175]        user_path_create+0x2d/0x50
[ 3437.466352]        bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs]
[ 3437.466617]        __x64_sys_ioctl+0x93/0xd0
[ 3437.466791]        do_syscall_64+0x42/0xf0
[ 3437.466957]        entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ 3437.467180]
               other info that might help us debug this:

[ 3437.469670] 2 locks held by bcachefs/35533:
               other info that might help us debug this:

[ 3437.467507] Chain exists of:
                 sb_writers#10 --> &c->snapshot_create_lock --> &type->s_umount_key#48

[ 3437.467979]  Possible unsafe locking scenario:

[ 3437.468223]        CPU0                    CPU1
[ 3437.468405]        ----                    ----
[ 3437.468585]   rlock(&type->s_umount_key#48);
[ 3437.468758]                                lock(&c->snapshot_create_lock);
[ 3437.469030]                                lock(&type->s_umount_key#48);
[ 3437.469291]   rlock(sb_writers#10);
[ 3437.469434]
                *** DEADLOCK ***

[ 3437.469670] 2 locks held by bcachefs/35533:
[ 3437.469838]  #0: ffffa0a02ce00a88 (&c->snapshot_create_lock){++++}-{3:3}, at: bch2_fs_file_ioctl+0x1e3/0xc90 [bcachefs]
[ 3437.470294]  thesofproject#1: ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]
[ 3437.470744]
               stack backtrace:
[ 3437.470922] CPU: 7 PID: 35533 Comm: bcachefs Kdump: loaded Tainted: G            E      6.7.0-rc7-custom+ thesofproject#85
[ 3437.471313] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
[ 3437.471694] Call Trace:
[ 3437.471795]  <TASK>
[ 3437.471884]  dump_stack_lvl+0x57/0x90
[ 3437.472035]  check_noncircular+0x132/0x150
[ 3437.472202]  __lock_acquire+0x1455/0x21b0
[ 3437.472369]  lock_acquire+0xc6/0x2b0
[ 3437.472518]  ? filename_create+0x62/0x190
[ 3437.472683]  ? lock_is_held_type+0x97/0x110
[ 3437.472856]  mnt_want_write+0x46/0x1a0
[ 3437.473025]  ? filename_create+0x62/0x190
[ 3437.473204]  filename_create+0x62/0x190
[ 3437.473380]  user_path_create+0x2d/0x50
[ 3437.473555]  bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs]
[ 3437.473819]  ? lock_acquire+0xc6/0x2b0
[ 3437.474002]  ? __fget_files+0x2a/0x190
[ 3437.474195]  ? __fget_files+0xbc/0x190
[ 3437.474380]  ? lock_release+0xc5/0x270
[ 3437.474567]  ? __x64_sys_ioctl+0x93/0xd0
[ 3437.474764]  ? __pfx_bch2_fs_file_ioctl+0x10/0x10 [bcachefs]
[ 3437.475090]  __x64_sys_ioctl+0x93/0xd0
[ 3437.475277]  do_syscall_64+0x42/0xf0
[ 3437.475454]  entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ 3437.475691] RIP: 0033:0x7f2743c313af
======================================================

In __bch2_ioctl_subvolume_create(), we grab s_umount unconditionally
and unlock it at the end of the function. There is a comment
"why do we need this lock?" about the lock coming from
commit 42d2373 ("bcachefs: Snapshot creation, deletion")
The reason is that __bch2_ioctl_subvolume_create() calls
sync_inodes_sb() which enforce locked s_umount to writeback all dirty
nodes before doing snapshot works.

Fix it by read locking s_umount for snapshotting only and unlocking
s_umount after sync_inodes_sb().

Signed-off-by: Su Yue <glass.su@suse.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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