Hi folks, I tested it on my DELL XPS desktop. And it won't show any warnings when I mounting pstore and deleting pstore items after this patch applied. Tested-by: Madper Xie cxie@xxxxxxxxxx writes: > Oops, It seems my mu4e(a email client for emacs)'s auto-indent breaks the > patch... I apologize for this... > > seiji.aguchi@xxxxxxx writes: > >> Hi Madper, >> >> I tested this patch on 3.12-rc4. >> Could you please send me the log when you failed to apply? >> >> Seiji >> >>> -----Original Message----- >>> From: Madper Xie [mailto:cxie@xxxxxxxxxx] >>> Sent: Thursday, October 17, 2013 1:54 AM >>> To: Seiji Aguchi >>> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-efi@xxxxxxxxxxxxxxx; matt.fleming@xxxxxxxxx; tony.luck@xxxxxxxxx; Tomoki Sekiyama; dle- >>> develop@xxxxxxxxxxxxxxxxxxxxx >>> Subject: Re: [PATCH v3] efivars,efi-pstore: Hold off deletion of sysfs entry until, the scan is completed >>> >>> Howdy Seiji, >>> I failed appily this patch to both 3.12-rc2 and 3.12-rc4. Could you >>> please let me know which is the right tree for this patch? >>> >>> Thanks, >>> Madper. >>> seiji.aguchi@xxxxxxx writes: >>> >>> > Change from v2: >>> > - Move dynamic memory allocation to efi_pstore_read() before holding >>> > efivars->lock to protect entry->var.Data. >>> > - Access to entry->scanning while holding efivars->lock. >>> > - Move a comment about a returned value from efi_pstore_read_func() to >>> > efi_pstore_read() because "size < 0" case may happen in efi_pstore_read(). >>> > >>> > Currently, when mounting pstore file system, a read callback of efi_pstore >>> > driver runs mutiple times as below. >>> > >>> > - In the first read callback, scan efivar_sysfs_list from head and pass >>> > a kmsg buffer of a entry to an upper pstore layer. >>> > - In the second read callback, rescan efivar_sysfs_list from the entry and pass >>> > another kmsg buffer to it. >>> > - Repeat the scan and pass until the end of efivar_sysfs_list. >>> > >>> > In this process, an entry is read across the multiple read function calls. >>> > To avoid race between the read and erasion, the whole process above is >>> > protected by a spinlock, holding in open() and releasing in close(). >>> > >>> > At the same time, kmemdup() is called to pass the buffer to pstore filesystem >>> > during it. >>> > And then, it causes a following lockdep warning. >>> > >>> > To make the dynamic memory allocation runnable without taking spinlock, >>> > holding off a deletion of sysfs entry if it happens while scanning it >>> > via efi_pstore, and deleting it after the scan is completed. >>> > >>> > To implement it, this patch introduces two flags, scanning and deleting, >>> > to efivar_entry. >>> > >>> > [ 1.143710] ------------[ cut here ]------------ >>> > [ 1.144058] WARNING: CPU: 1 PID: 1 at kernel/lockdep.c:2740 >>> > lockdep_trace_alloc+0x104/0x110() >>> > [ 1.144058] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) >>> > [ 1.144058] Modules linked in: >>> > >>> > [ 1.144058] CPU: 1 PID: 1 Comm: systemd Not tainted 3.11.0-rc5 #2 >>> > [ 1.144058] 0000000000000009 ffff8800797e9ae0 ffffffff816614a5 >>> > ffff8800797e9b28 >>> > [ 1.144058] ffff8800797e9b18 ffffffff8105510d 0000000000000080 >>> > 0000000000000046 >>> > [ 1.144058] 00000000000000d0 00000000000003af ffffffff81ccd0c0 >>> > ffff8800797e9b78 >>> > [ 1.144058] Call Trace: >>> > [ 1.144058] [<ffffffff816614a5>] dump_stack+0x54/0x74 >>> > [ 1.144058] [<ffffffff8105510d>] warn_slowpath_common+0x7d/0xa0 >>> > [ 1.144058] [<ffffffff8105517c>] warn_slowpath_fmt+0x4c/0x50 >>> > [ 1.144058] [<ffffffff8131290f>] ? vsscanf+0x57f/0x7b0 >>> > [ 1.144058] [<ffffffff810bbd74>] lockdep_trace_alloc+0x104/0x110 >>> > [ 1.144058] [<ffffffff81192da0>] __kmalloc_track_caller+0x50/0x280 >>> > [ 1.144058] [<ffffffff815147bb>] ? >>> > efi_pstore_read_func.part.1+0x12b/0x170 >>> > [ 1.144058] [<ffffffff8115b260>] kmemdup+0x20/0x50 >>> > [ 1.144058] [<ffffffff815147bb>] efi_pstore_read_func.part.1+0x12b/0x170 >>> > [ 1.144058] [<ffffffff81514800>] ? >>> > efi_pstore_read_func.part.1+0x170/0x170 >>> > [ 1.144058] [<ffffffff815148b4>] efi_pstore_read_func+0xb4/0xe0 >>> > [ 1.144058] [<ffffffff81512b7b>] __efivar_entry_iter+0xfb/0x120 >>> > [ 1.144058] [<ffffffff8151428f>] efi_pstore_read+0x3f/0x50 >>> > [ 1.144058] [<ffffffff8128d7ba>] pstore_get_records+0x9a/0x150 >>> > [ 1.158207] [<ffffffff812af25c>] ? selinux_d_instantiate+0x1c/0x20 >>> > [ 1.158207] [<ffffffff8128ce30>] ? parse_options+0x80/0x80 >>> > [ 1.158207] [<ffffffff8128ced5>] pstore_fill_super+0xa5/0xc0 >>> > [ 1.158207] [<ffffffff811ae7d2>] mount_single+0xa2/0xd0 >>> > [ 1.158207] [<ffffffff8128ccf8>] pstore_mount+0x18/0x20 >>> > [ 1.158207] [<ffffffff811ae8b9>] mount_fs+0x39/0x1b0 >>> > [ 1.158207] [<ffffffff81160550>] ? __alloc_percpu+0x10/0x20 >>> > [ 1.158207] [<ffffffff811c9493>] vfs_kern_mount+0x63/0xf0 >>> > [ 1.158207] [<ffffffff811cbb0e>] do_mount+0x23e/0xa20 >>> > [ 1.158207] [<ffffffff8115b51b>] ? strndup_user+0x4b/0xf0 >>> > [ 1.158207] [<ffffffff811cc373>] SyS_mount+0x83/0xc0 >>> > [ 1.158207] [<ffffffff81673cc2>] system_call_fastpath+0x16/0x1b >>> > [ 1.158207] ---[ end trace 61981bc62de9f6f4 ]--- >>> > >>> > Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx> >>> > --- >>> > drivers/firmware/efi/efi-pstore.c | 143 +++++++++++++++++++++++++++++++++++--- >>> > drivers/firmware/efi/efivars.c | 12 ++-- >>> > drivers/firmware/efi/vars.c | 12 +++- >>> > include/linux/efi.h | 2 + >>> > 4 files changed, 153 insertions(+), 16 deletions(-) >>> > >>> > diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c >>> > index 5002d50..ebd5dbc 100644 >>> > --- a/drivers/firmware/efi/efi-pstore.c >>> > +++ b/drivers/firmware/efi/efi-pstore.c >>> > @@ -18,14 +18,12 @@ module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644); >>> > >>> > static int efi_pstore_open(struct pstore_info *psi) >>> > { >>> > - efivar_entry_iter_begin(); >>> > psi->data = NULL; >>> > return 0; >>> > } >>> > >>> > static int efi_pstore_close(struct pstore_info *psi) >>> > { >>> > - efivar_entry_iter_end(); >>> > psi->data = NULL; >>> > return 0; >>> > } >>> > @@ -91,19 +89,125 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data) >>> > __efivar_entry_get(entry, &entry->var.Attributes, >>> > &entry->var.DataSize, entry->var.Data); >>> > size = entry->var.DataSize; >>> > + memcpy(*cb_data->buf, entry->var.Data, (size_t)min_t(unsigned long, >>> > + 1024, size)); >>> > >>> > - *cb_data->buf = kmemdup(entry->var.Data, size, GFP_KERNEL); >>> > - if (*cb_data->buf == NULL) >>> > - return -ENOMEM; >>> > return size; >>> > } >>> > >>> > +/** >>> > + * efi_pstore_scan_sysfs_enter >>> > + * @entry: scanning entry >>> > + * @next: next entry >>> > + * @head: list head >>> > + */ >>> > +static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos, >>> > + struct efivar_entry *next, >>> > + struct list_head *head) >>> > +{ >>> > + pos->scanning = true; >>> > + if (&next->list != head) >>> > + next->scanning = true; >>> > +} >>> > + >>> > +/** >>> > + * __efi_pstore_scan_sysfs_exit >>> > + * @entry: deleting entry >>> > + * @turn_off_scanning: Check if a scanning flag should be turned off >>> > + */ >>> > +static inline void __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry, >>> > + bool turn_off_scanning) >>> > +{ >>> > + if (entry->deleting) { >>> > + list_del(&entry->list); >>> > + efivar_entry_iter_end(); >>> > + efivar_unregister(entry); >>> > + efivar_entry_iter_begin(); >>> > + } else if (turn_off_scanning) >>> > + entry->scanning = false; >>> > +} >>> > + >>> > +/** >>> > + * efi_pstore_scan_sysfs_exit >>> > + * @pos: scanning entry >>> > + * @next: next entry >>> > + * @head: list head >>> > + * @stop: a flag checking if scanning will stop >>> > + */ >>> > +static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos, >>> > + struct efivar_entry *next, >>> > + struct list_head *head, bool stop) >>> > +{ >>> > + __efi_pstore_scan_sysfs_exit(pos, true); >>> > + if (stop) >>> > + __efi_pstore_scan_sysfs_exit(next, &next->list != head); >>> > +} >>> > + >>> > +/** >>> > + * efi_pstore_sysfs_entry_iter >>> > + * >>> > + * @data: function-specific data to pass to callback >>> > + * @pos: entry to begin iterating from >>> > + * >>> > + * You MUST call efivar_enter_iter_begin() before this function, and >>> > + * efivar_entry_iter_end() afterwards. >>> > + * >>> > + * It is possible to begin iteration from an arbitrary entry within >>> > + * the list by passing @pos. @pos is updated on return to point to >>> > + * the next entry of the last one passed to efi_pstore_read_func(). >>> > + * To begin iterating from the beginning of the list @pos must be %NULL. >>> > + */ >>> > +static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos) >>> > +{ >>> > + struct efivar_entry *entry, *n; >>> > + struct list_head *head = &efivar_sysfs_list; >>> > + int size = 0; >>> > + >>> > + if (!*pos) { >>> > + list_for_each_entry_safe(entry, n, head, list) { >>> > + efi_pstore_scan_sysfs_enter(entry, n, head); >>> > + >>> > + size = efi_pstore_read_func(entry, data); >>> > + efi_pstore_scan_sysfs_exit(entry, n, head, size < 0); >>> > + if (size) >>> > + break; >>> > + } >>> > + *pos = n; >>> > + return size; >>> > + } >>> > + >>> > + list_for_each_entry_safe_from((*pos), n, head, list) { >>> > + efi_pstore_scan_sysfs_enter((*pos), n, head); >>> > + >>> > + size = efi_pstore_read_func((*pos), data); >>> > + efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0); >>> > + if (size) >>> > + break; >>> > + } >>> > + *pos = n; >>> > + return size; >>> > +} >>> > + >>> > +/** >>> > + * efi_pstore_read >>> > + * >>> > + * This function returns a size of NVRAM entry logged via efi_pstore_write(). >>> > + * The meaning and behavior of efi_pstore/pstore are as below. >>> > + * >>> > + * size > 0: Got data of an entry logged via efi_pstore_write() successfully, >>> > + * and pstore filesystem will continue reading subsequent entries. >>> > + * size == 0: Entry was not logged via efi_pstore_write(), >>> > + * and efi_pstore driver will continue reading subsequent entries. >>> > + * size < 0: Failed to get data of entry logging via efi_pstore_write(), >>> > + * and pstore will stop reading entry. >>> > + */ >>> > static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, >>> > int *count, struct timespec *timespec, >>> > char **buf, bool *compressed, >>> > struct pstore_info *psi) >>> > { >>> > struct pstore_read_data data; >>> > + ssize_t size; >>> > >>> > data.id = id; >>> > data.type = type; >>> > @@ -112,8 +216,17 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, >>> > data.compressed = compressed; >>> > data.buf = buf; >>> > >>> > - return __efivar_entry_iter(efi_pstore_read_func, &efivar_sysfs_list, &data, >>> > - (struct efivar_entry **)&psi->data); >>> > + *data.buf = kzalloc(1024, GFP_KERNEL); >>> > + if (!*data.buf) >>> > + return -ENOMEM; >>> > + >>> > + efivar_entry_iter_begin(); >>> > + size = efi_pstore_sysfs_entry_iter(&data, >>> > + (struct efivar_entry **)&psi->data); >>> > + efivar_entry_iter_end(); >>> > + if (size <= 0) >>> > + kfree(*data.buf); >>> > + return size; >>> > } >>> > >>> > static int efi_pstore_write(enum pstore_type_id type, >>> > @@ -184,9 +297,17 @@ static int efi_pstore_erase_func(struct efivar_entry *entry, void *data) >>> > return 0; >>> > } >>> > >>> > + if (entry->scanning) { >>> > + /* >>> > + * Skip deletion because this entry will be deleted >>> > + * after scanning is completed. >>> > + */ >>> > + entry->deleting = true; >>> > + } else >>> > + list_del(&entry->list); >>> > + >>> > /* found */ >>> > __efivar_entry_delete(entry); >>> > - list_del(&entry->list); >>> > >>> > return 1; >>> > } >>> > @@ -214,10 +335,12 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count, >>> > >>> > efivar_entry_iter_begin(); >>> > found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry); >>> > - efivar_entry_iter_end(); >>> > >>> > - if (found) >>> > + if (found && !entry->scanning) { >>> > + efivar_entry_iter_end(); >>> > efivar_unregister(entry); >>> > + } else >>> > + efivar_entry_iter_end(); >>> > >>> > return 0; >>> > } >>> > diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c >>> > index 8a7432a..8c5a61a 100644 >>> > --- a/drivers/firmware/efi/efivars.c >>> > +++ b/drivers/firmware/efi/efivars.c >>> > @@ -383,12 +383,16 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, >>> > else if (__efivar_entry_delete(entry)) >>> > err = -EIO; >>> > >>> > - efivar_entry_iter_end(); >>> > - >>> > - if (err) >>> > + if (err) { >>> > + efivar_entry_iter_end(); >>> > return err; >>> > + } >>> > >>> > - efivar_unregister(entry); >>> > + if (!entry->scanning) { >>> > + efivar_entry_iter_end(); >>> > + efivar_unregister(entry); >>> > + } else >>> > + efivar_entry_iter_end(); >>> > >>> > /* It's dead Jim.... */ >>> > return count; >>> > diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c >>> > index 391c67b..b22659c 100644 >>> > --- a/drivers/firmware/efi/vars.c >>> > +++ b/drivers/firmware/efi/vars.c >>> > @@ -683,8 +683,16 @@ struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid, >>> > if (!found) >>> > return NULL; >>> > >>> > - if (remove) >>> > - list_del(&entry->list); >>> > + if (remove) { >>> > + if (entry->scanning) { >>> > + /* >>> > + * The entry will be deleted >>> > + * after scanning is completed. >>> > + */ >>> > + entry->deleting = true; >>> > + } else >>> > + list_del(&entry->list); >>> > + } >>> > >>> > return entry; >>> > } >>> > diff --git a/include/linux/efi.h b/include/linux/efi.h >>> > index 5f8f176..04088fb 100644 >>> > --- a/include/linux/efi.h >>> > +++ b/include/linux/efi.h >>> > @@ -782,6 +782,8 @@ struct efivar_entry { >>> > struct efi_variable var; >>> > struct list_head list; >>> > struct kobject kobj; >>> > + bool scanning; >>> > + bool deleting; >>> > }; >>> > >>> > extern struct list_head efivar_sysfs_list; >>> >>> >>> -- >>> Best, >>> Madper Xie. -- Best, Madper Xie. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
