diff options
| author | Qian Cai <cai@redhat.com> | 2020-10-28 11:27:17 -0400 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-11-02 12:54:20 +1100 |
| commit | fd552e0542b4532483289cce48fdbd27b692984b (patch) | |
| tree | cb8c7d78cc69a8cf448e5a3e6c441177011ad1a3 /arch/powerpc/kernel/eeh_cache.c | |
| parent | 3cea11cd5e3b00d91caf0b4730194039b45c5891 (diff) | |
| download | linux-fd552e0542b4532483289cce48fdbd27b692984b.tar.gz linux-fd552e0542b4532483289cce48fdbd27b692984b.tar.bz2 linux-fd552e0542b4532483289cce48fdbd27b692984b.zip | |
powerpc/eeh_cache: Fix a possible debugfs deadlock
Lockdep complains that a possible deadlock below in
eeh_addr_cache_show() because it is acquiring a lock with IRQ enabled,
but eeh_addr_cache_insert_dev() needs to acquire the same lock with IRQ
disabled. Let's just make eeh_addr_cache_show() acquire the lock with
IRQ disabled as well.
CPU0 CPU1
---- ----
lock(&pci_io_addr_cache_root.piar_lock);
local_irq_disable();
lock(&tp->lock);
lock(&pci_io_addr_cache_root.piar_lock);
<Interrupt>
lock(&tp->lock);
*** DEADLOCK ***
lock_acquire+0x140/0x5f0
_raw_spin_lock_irqsave+0x64/0xb0
eeh_addr_cache_insert_dev+0x48/0x390
eeh_probe_device+0xb8/0x1a0
pnv_pcibios_bus_add_device+0x3c/0x80
pcibios_bus_add_device+0x118/0x290
pci_bus_add_device+0x28/0xe0
pci_bus_add_devices+0x54/0xb0
pcibios_init+0xc4/0x124
do_one_initcall+0xac/0x528
kernel_init_freeable+0x35c/0x3fc
kernel_init+0x24/0x148
ret_from_kernel_thread+0x5c/0x80
lock_acquire+0x140/0x5f0
_raw_spin_lock+0x4c/0x70
eeh_addr_cache_show+0x38/0x110
seq_read+0x1a0/0x660
vfs_read+0xc8/0x1f0
ksys_read+0x74/0x130
system_call_exception+0xf8/0x1d0
system_call_common+0xe8/0x218
Fixes: 5ca85ae6318d ("powerpc/eeh_cache: Add a way to dump the EEH address cache")
Signed-off-by: Qian Cai <cai@redhat.com>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201028152717.8967-1-cai@redhat.com
Diffstat (limited to 'arch/powerpc/kernel/eeh_cache.c')
| -rw-r--r-- | arch/powerpc/kernel/eeh_cache.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/eeh_cache.c b/arch/powerpc/kernel/eeh_cache.c index 6b50bf15d8c1..bf3270426d82 100644 --- a/arch/powerpc/kernel/eeh_cache.c +++ b/arch/powerpc/kernel/eeh_cache.c @@ -264,8 +264,9 @@ static int eeh_addr_cache_show(struct seq_file *s, void *v) { struct pci_io_addr_range *piar; struct rb_node *n; + unsigned long flags; - spin_lock(&pci_io_addr_cache_root.piar_lock); + spin_lock_irqsave(&pci_io_addr_cache_root.piar_lock, flags); for (n = rb_first(&pci_io_addr_cache_root.rb_root); n; n = rb_next(n)) { piar = rb_entry(n, struct pci_io_addr_range, rb_node); @@ -273,7 +274,7 @@ static int eeh_addr_cache_show(struct seq_file *s, void *v) (piar->flags & IORESOURCE_IO) ? "i/o" : "mem", &piar->addr_lo, &piar->addr_hi, pci_name(piar->pcidev)); } - spin_unlock(&pci_io_addr_cache_root.piar_lock); + spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags); return 0; } |