linux-toradex.git/drivers/pci/slot.c, branch v4.9.78

PCI: Hold pci_slot_mutex while searching bus->slots list

2015-07-30T21:19:53+00:00

Previously, pci_setup_device() and similar functions searched the
pci_bus->slots list without any locking.  It was possible for another
thread to update the list while we searched it.

Add pci_dev_assign_slot() to search the list while holding pci_slot_mutex.

[bhelgaas: changelog, fold in CONFIG_SYSFS fix]
Tested-by: Guenter Roeck 
Signed-off-by: Yijing Wang 
Signed-off-by: Bjorn Helgaas

PCI: Protect pci_bus->slots with pci_slot_mutex, not pci_bus_sem

2015-07-30T20:49:10+00:00

Rajat Jain reported a deadlock when PCIe hot-add and AER recovery happen at
the same time:

thread 1:

  pciehp_enable_slot
    pciehp_configure_device
      pci_bus_add_devices
        pci_bus_add_device
          device_attach
            device_lock(dev)                       # acquire device lock
            ...
            pciehp_probe
              init_slot
                pci_hp_register
                  pci_create_slot
                    down_write(pci_bus_sem)        # deadlock here

thread 2:

  aer_isr_one_error
    aer_process_err_device
      do_recovery
        broadcast_error_message(..., report_error_detected)
          pci_walk_bus(..., cb=report_error_detected, ...)
            down_read(&pci_bus_sem)                # acquire pci_bus_sem
            report_error_detected(dev)             # cb()
              device_lock(dev)                     # deadlock here

Previously, the bus->devices and bus->slots list were protected by
pci_bus_sem.  In pci_create_slot(), we held it for writing so we could
add to the bus->slots list.

Add a new local pci_slot_mutex to protect bus->slots.  Hold pci_bus_sem for
reading while searching the bus->devices list.

[bhelgaas: changelog]
Link: http://lkml.kernel.org/r/CAA93t1qpPqbih+UB0McA_d_+2rVaNkXsinAUxYzK9+JXSS+L-g@mail.gmail.com
Reported-by: Rajat Jain 
Tested-by: Guenter Roeck 
Signed-off-by: Yijing Wang 
Signed-off-by: Bjorn Helgaas

VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms.

2014-03-24T01:51:00+00:00

Summary of http://lkml.org/lkml/2014/3/14/363 :

  Ted: module_param(queue_depth, int, 444)
  Joe: 0444!
  Rusty: User perms >= group perms >= other perms?
  Joe: CLASS_ATTR, DEVICE_ATTR, SENSOR_ATTR and SENSOR_ATTR_2?

Side effect of stricter permissions means removing the unnecessary
S_IFREG from several callers.

Note that the BUILD_BUG_ON_ZERO((perm) & 2) test was removed: a fair
number of drivers fail this test, so that will be the debate for a
future patch.

Suggested-by: Joe Perches 
Acked-by: Bjorn Helgaas  for drivers/pci/slot.c
Acked-by: Greg Kroah-Hartman 
Cc: Miklos Szeredi 
Cc: Mark Fasheh 
Cc: Joel Becker 
Signed-off-by: Rusty Russell

PCI: Remove unused pci_renumber_slot()

2014-01-13T18:14:44+00:00

My philosophy is unused code is dead code.  And dead code is subject to bit
rot and is a likely source of bugs.  Use it or lose it.

This reverts part of f46753c5e354 ("PCI: introduce pci_slot") and
d25b7c8d6ba2 ("PCI: rename pci_update_slot_number to pci_renumber_slot"),
removing this interface:

    pci_renumber_slot()

[bhelgaas: split to separate patch, add historical link from Alex]
Link: http://lkml.kernel.org/r/20081009043140.8678.44164.stgit@bob.kio
Signed-off-by: Stephen Hemminger 
Signed-off-by: Bjorn Helgaas 
Acked-by: Alex Chiang

PCI: Fix whitespace, capitalization, and spelling errors

2013-11-14T18:28:18+00:00

Fix whitespace, capitalization, and spelling errors.  No functional change.
I know "busses" is not an error, but "buses" was more common, so I used it
consistently.

Signed-off-by: Marta Rybczynska  (pci_reset_bridge_secondary_bus())
Signed-off-by: Bjorn Helgaas 
Acked-by: Rafael J. Wysocki

PCI: Warn about failures instead of "must_check" functions

2013-04-17T16:21:12+00:00

These places capture return values to avoid "must_check" warnings,
but we didn't *do* anything with the return values, which causes
"set but not used" warnings.  We might as well do something instead
of just trying to evade the "must_check" warnings.

Signed-off-by: Bjorn Helgaas

pci: add module.h to files implicitly relying on its presence.

2011-10-31T23:31:23+00:00

These were getting module.h implicitly from device.h but we want
to clean that up, so we fix it here to avoid things like:

pci/slot.c: In function ‘pci_hp_create_module_link’:
pci/slot.c:383: error: ‘module_kset’ undeclared (first use in this function)

Similarly, rpadlpar_core.c is modular, so add module.h to its includes.

Signed-off-by: Paul Gortmaker

PCI: bus speed strings should be const

2010-08-31T22:28:00+00:00

Signed-off-by: Stephen Hemminger 
Signed-off-by: Jesse Barnes

Revert "PCI: create function symlinks in /sys/bus/pci/slots/N/"

2010-06-11T20:08:37+00:00

This reverts commit 75568f8094eb0333e9c2109b23cbc8b82d318a3c.

Since they're just a convenience anyway, remove these symlinks since
they're causing duplicate filename errors in the wild.

Acked-by: Alex Chiang 
Signed-off-by: Jesse Barnes

PCI: create function symlinks in /sys/bus/pci/slots/N/

2010-05-11T19:01:07+00:00

Create convenience symlinks in sysfs, linking slots to device
functions, and vice versa. These links make it easier for users to
figure out which devices actually live in what slots.

For example:

sapphire:/sys/bus/pci/slots # ls
1  10  2  3  4  5  6  7  8  9

sapphire:/sys/bus/pci/slots # ls -l 3
total 0
-r--r--r-- 1 root root 65536 Aug 18 14:10 address
lrwxrwxrwx 1 root root     0 Aug 18 14:10 function0 ->
../../../../devices/pci0000:23/0000:23:01.0
lrwxrwxrwx 1 root root     0 Aug 18 14:10 function1 ->
../../../../devices/pci0000:23/0000:23:01.1

sapphire:/sys/bus/pci/slots # ls -l 3/function0/slot
lrwxrwxrwx 1 root root 0 Aug 18 14:13 3/function0/slot ->
../../../bus/pci/slots/3

The original form of this patch was written by Matthew Wilcox,
and was enhanced to include links from the sysfs slots/ directory
pointing back at the device functions.

Cc: willy@linux.intel.com
Signed-off-by: Alex Chiang 
Signed-off-by: Jesse Barnes