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
