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2011-11-17pstore: pass allocated memory region back to callerKees Cook1-5/+8
The buf_lock cannot be held while populating the inodes, so make the backend pass forward an allocated and filled buffer instead. This solves the following backtrace. The effect is that "buf" is only ever used to notify the backends that something was written to it, and shouldn't be used in the read path. To replace the buf_lock during the read path, isolate the open/read/close loop with a separate mutex to maintain serialized access to the backend. Note that is is up to the pstore backend to cope if the (*write)() path is called in the middle of the read path. [ 59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847 [ 59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount [ 59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1 [ 59.691019] Call Trace: [ 59.691019] [<810252d5>] __might_sleep+0xc3/0xca [ 59.691019] [<810a26e6>] kmem_cache_alloc+0x32/0xf3 [ 59.691019] [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4 [ 59.691019] [<810b68b1>] alloc_inode+0x2a/0x64 [ 59.691019] [<810b6903>] new_inode+0x18/0x43 [ 59.691019] [<81142447>] pstore_get_inode.isra.1+0x11/0x98 [ 59.691019] [<81142623>] pstore_mkfile+0xae/0x26f [ 59.691019] [<810a2a66>] ? kmem_cache_free+0x19/0xb1 [ 59.691019] [<8116c821>] ? ida_get_new_above+0x140/0x158 [ 59.691019] [<811708ea>] ? __init_rwsem+0x1e/0x2c [ 59.691019] [<810b67e8>] ? inode_init_always+0x111/0x1b0 [ 59.691019] [<8102127e>] ? should_resched+0xd/0x27 [ 59.691019] [<8137977f>] ? _cond_resched+0xd/0x21 [ 59.691019] [<81142abf>] pstore_get_records+0x52/0xa7 [ 59.691019] [<8114254b>] pstore_fill_super+0x7d/0x91 [ 59.691019] [<810a7ff5>] mount_single+0x46/0x82 [ 59.691019] [<8114231a>] pstore_mount+0x15/0x17 [ 59.691019] [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98 [ 59.691019] [<810a8199>] mount_fs+0x5a/0x12d [ 59.691019] [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a [ 59.691019] [<810b9474>] vfs_kern_mount+0x4f/0x7d [ 59.691019] [<810b9d7e>] do_kern_mount+0x34/0xb2 [ 59.691019] [<810bb15f>] do_mount+0x5fc/0x64a [ 59.691019] [<810912fb>] ? strndup_user+0x2e/0x3f [ 59.691019] [<810bb3cb>] sys_mount+0x66/0x99 [ 59.691019] [<8137b537>] sysenter_do_call+0x12/0x26 Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-10-12pstore: make pstore write function return normal success/fail valueChen Gong1-5/+6
Currently pstore write interface employs record id as return value, but it is not enough because it can't tell caller if the write operation is successful. Pass the record id back via an argument pointer and return zero for success, non-zero for failure. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-08-16pstore: change mutex locking to spin_locksDon Zickus1-7/+21
pstore was using mutex locking to protect read/write access to the backend plug-ins. This causes problems when pstore is executed in an NMI context through panic() -> kmsg_dump(). This patch changes the mutex to a spin_lock_irqsave then also checks to see if we are in an NMI context. If we are in an NMI and can't get the lock, just print a message stating that and blow by the locking. All this is probably a hack around the bigger locking problem but it solves my current situation of trying to sleep in an NMI context. Tested by loading the lkdtm module and executing a HARDLOCKUP which will cause the machine to panic inside the nmi handler. Signed-off-by: Don Zickus <dzickus@redhat.com> Acked-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-08-16pstore: defer inserting OOPS entries into pstoreLuck, Tony3-14/+82
Life is simple for all the kernel terminating types of kmsg_dump call backs - pstore just saves the tail end of the console log. But for "oops" the situation is more complex - the kernel may carry on running (possibly for ever). So we'd like to make the logged copy of the oops appear in the pstore filesystem - so that the user has a handle to clear the entry from the persistent backing store (if we don't, the store may fill with "oops" entries (that are also safely stashed in /var/log/messages) leaving no space for real errors. Current code calls pstore_mkfile() immediately. But this may not be safe. The oops could have happened with arbitrary locks held, or in interrupt or NMI context. So allocating memory and calling into generic filesystem code seems unwise. This patch defers making the entry appear. At the time of the oops, we merely set a flag "pstore_new_entry" noting that a new entry has been added. A periodic timer checks once a minute to see if the flag is set - if so, it schedules a work queue to rescan the backing store and make all new entries appear in the pstore filesystem. Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Allow the user to explicitly choose a backendMatthew Garrett1-0/+11
pstore only allows one backend to be registered at present, but the system may provide several. Add a parameter to allow the user to choose which backend will be used rather than just relying on load order. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Make "part" unsignedMatthew Garrett1-1/+2
We'll never have a negative part, so just make this an unsigned int. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Add extra context for writes and erasesMatthew Garrett2-6/+9
EFI only provides small amounts of individual storage, and conventionally puts metadata in the storage variable name. Rather than add a metadata header to the (already limited) variable storage, it's easier for us to modify pstore to pass all the information we need to construct a unique variable name to the appropriate functions. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Extend API for more flexibility in new backendsMatthew Garrett3-12/+13
Some pstore implementations may not have a static context, so extend the API to pass the pstore_info struct to all calls and allow for a context pointer. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-05-16pstore: fix pstore filesystem mount/remount issueChen Gong1-1/+7
Currently after mount/remount operation on pstore filesystem, the content on pstore will be lost. It is because current ERST implementation doesn't support multi-user usage, which moves internal pointer to the end after accessing it. Adding multi-user support for pstore usage. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-05-16pstore: fix one type of return value in pstoreChen Gong1-2/+2
the return type of function _read_ in pstore is size_t, but in the callback function of _read_, the logic doesn't consider it too much, which means if negative value (assuming error here) is returned, it will be converted to positive because of type casting. ssize_t is enough for this function. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-03-31Fix common misspellingsLucas De Marchi1-1/+1
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-22pstore: cleanups to pstore_dump()Tony Luck1-3/+12
pstore_dump() can be called with many different "reason" codes. Save the name of the code in the persistent store record. Also - only worthwhile calling pstore_mkfile for KMSG_DUMP_OOPS - that is the only one where the kernel will continue running. Reviewed-by: Seiji Aguchi <seiji.aguchi@hds.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-03-21pstore: use mount option instead sysfs to tweak kmsg_bytesLuck, Tony3-37/+50
/sys/fs is a somewhat strange way to tweak what could more obviously be tuned with a mount option. Suggested-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-21pstore: fix leaking ->i_privateTony Luck1-1/+7
Move kfree() of i_private out of ->unlink() and into ->evict_inode() Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-17Some fixes for pstoreTony Luck1-60/+56
1) Change from ->get_sb() to ->mount() 2) Use mount_single() instead of mount_nodev() 3) Pulled in ramfs_get_inode() & trimmed to what I need for pstore 4) Drop the ugly pstore_writefile() Just save data using kmalloc() and provide a pstore_file_read() that uses simple_read_from_buffer(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-06pstore: fix build warning for unused return value from sysfs_create_fileTony Luck1-11/+16
fs/pstore/inode.c: In function 'init_pstore_fs': fs/pstore/inode.c:266: warning: ignoring return value of 'sysfs_create_file', declared with attribute warn_unused_result Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Tony Luck <tony.luck@intel.com>
2010-12-28pstore: new filesystem interface to platform persistent storageTony Luck5-0/+509
Some platforms have a small amount of non-volatile storage that can be used to store information useful to diagnose the cause of a system crash. This is the generic part of a file system interface that presents information from the crash as a series of files in /dev/pstore. Once the information has been seen, the underlying storage is freed by deleting the files. Signed-off-by: Tony Luck <tony.luck@intel.com>
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