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2020-10-16Merge tag 'printk-for-5.10-fixup' of ↵Linus Torvalds1-1/+4
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk fix from Petr Mladek: "Prevent overflow in the new lockless ringbuffer" * tag 'printk-for-5.10-fixup' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: ringbuffer: Wrong data pointer when appending small string
2020-10-16Merge branch 'for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial Pull trivial updates from Jiri Kosina: "The latest advances in computer science from the trivial queue" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: xtensa: fix Kconfig typo spelling.txt: Remove some duplicate entries mtd: rawnand: oxnas: cleanup/simplify code selftests: vm: add fragment CONFIG_GUP_BENCHMARK perf: Fix opt help text for --no-bpf-event HID: logitech-dj: Fix spelling in comment bootconfig: Fix kernel message mentioning CONFIG_BOOT_CONFIG MAINTAINERS: rectify MMP SUPPORT after moving cputype.h scif: Fix spelling of EACCES printk: fix global comment lib/bitmap.c: fix spello fs: Fix missing 'bit' in comment
2020-10-15printk: ringbuffer: Wrong data pointer when appending small stringPetr Mladek1-1/+4
data_realloc() returns wrong data pointer when the block is wrapped and the size is not increased. It might happen when pr_cont() wants to add only few characters and there is already a space for them because of alignment. It might cause writing outsite the buffer. It has been detected by LTP tests with KASAN enabled: [ 221.921944] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=c,mems_allowed=0,oom_memcg=/0,task_memcg=in [ 221.922108] ================================================================== [ 221.922111] BUG: KASAN: global-out-of-bounds in vprintk_store+0x362/0x3d0 [ 221.922112] Write of size 2 at addr ffffffffba51dbcd by task memcg_test_1/11282 [ 221.922113] [ 221.922114] CPU: 1 PID: 11282 Comm: memcg_test_1 Not tainted 5.9.0-next-20201013 #1 [ 221.922116] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS 2.0b 07/27/2017 [ 221.922116] Call Trace: [ 221.922117] dump_stack+0xa4/0xd9 [ 221.922118] print_address_description.constprop.0+0x21/0x210 [ 221.922119] ? _raw_write_lock_bh+0xe0/0xe0 [ 221.922120] ? vprintk_store+0x362/0x3d0 [ 221.922121] kasan_report.cold+0x37/0x7c [ 221.922122] ? vprintk_store+0x362/0x3d0 [ 221.922123] check_memory_region+0x18c/0x1f0 [ 221.922124] memcpy+0x3c/0x60 [ 221.922125] vprintk_store+0x362/0x3d0 [ 221.922125] ? __ia32_sys_syslog+0x50/0x50 [ 221.922126] ? _raw_spin_lock_irqsave+0x9b/0x100 [ 221.922127] ? _raw_spin_lock_irq+0xf0/0xf0 [ 221.922128] ? __kasan_check_write+0x14/0x20 [ 221.922129] vprintk_emit+0x8d/0x1f0 [ 221.922130] vprintk_default+0x1d/0x20 [ 221.922131] vprintk_func+0x5a/0x100 [ 221.922132] printk+0xb2/0xe3 [ 221.922133] ? swsusp_write.cold+0x189/0x189 [ 221.922134] ? kernfs_vfs_xattr_set+0x60/0x60 [ 221.922134] ? _raw_write_lock_bh+0xe0/0xe0 [ 221.922135] ? trace_hardirqs_on+0x38/0x100 [ 221.922136] pr_cont_kernfs_path.cold+0x49/0x4b [ 221.922137] mem_cgroup_print_oom_context.cold+0x74/0xc3 [ 221.922138] dump_header+0x340/0x3bf [ 221.922139] oom_kill_process.cold+0xb/0x10 [ 221.922140] out_of_memory+0x1e9/0x860 [ 221.922141] ? oom_killer_disable+0x210/0x210 [ 221.922142] mem_cgroup_out_of_memory+0x198/0x1c0 [ 221.922143] ? mem_cgroup_count_precharge_pte_range+0x250/0x250 [ 221.922144] try_charge+0xa9b/0xc50 [ 221.922145] ? arch_stack_walk+0x9e/0xf0 [ 221.922146] ? memory_high_write+0x230/0x230 [ 221.922146] ? avc_has_extended_perms+0x830/0x830 [ 221.922147] ? stack_trace_save+0x94/0xc0 [ 221.922148] ? stack_trace_consume_entry+0x90/0x90 [ 221.922149] __memcg_kmem_charge+0x73/0x120 [ 221.922150] ? cred_has_capability+0x10f/0x200 [ 221.922151] ? mem_cgroup_can_attach+0x260/0x260 [ 221.922152] ? selinux_sb_eat_lsm_opts+0x2f0/0x2f0 [ 221.922153] ? obj_cgroup_charge+0x16b/0x220 [ 221.922154] ? kmem_cache_alloc+0x78/0x4c0 [ 221.922155] obj_cgroup_charge+0x122/0x220 [ 221.922156] ? vm_area_alloc+0x20/0x90 [ 221.922156] kmem_cache_alloc+0x78/0x4c0 [ 221.922157] vm_area_alloc+0x20/0x90 [ 221.922158] mmap_region+0x3ed/0x9a0 [ 221.922159] ? cap_mmap_addr+0x1d/0x80 [ 221.922160] do_mmap+0x3ee/0x720 [ 221.922161] vm_mmap_pgoff+0x16a/0x1c0 [ 221.922162] ? randomize_stack_top+0x90/0x90 [ 221.922163] ? copy_page_range+0x1980/0x1980 [ 221.922163] ksys_mmap_pgoff+0xab/0x350 [ 221.922164] ? find_mergeable_anon_vma+0x110/0x110 [ 221.922165] ? __audit_syscall_entry+0x1a6/0x1e0 [ 221.922166] __x64_sys_mmap+0x8d/0xb0 [ 221.922167] do_syscall_64+0x38/0x50 [ 221.922168] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 221.922169] RIP: 0033:0x7fe8f5e75103 [ 221.922172] Code: 54 41 89 d4 55 48 89 fd 53 4c 89 cb 48 85 ff 74 56 49 89 d9 45 89 f8 45 89 f2 44 89 e2 4c 89 ee 48 89 ef b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7d 5b 5d 41 5c 41 5d 41 5e 41 5f c3 66 2e 0f [ 221.922173] RSP: 002b:00007ffd38c90198 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 [ 221.922175] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe8f5e75103 [ 221.922176] RDX: 0000000000000003 RSI: 0000000000001000 RDI: 0000000000000000 [ 221.922178] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 221.922179] R10: 0000000000002022 R11: 0000000000000246 R12: 0000000000000003 [ 221.922180] R13: 0000000000001000 R14: 0000000000002022 R15: 0000000000000000 [ 221.922181] [ 213O[ 221.922182] The buggy address belongs to the variable: [ 221.922183] clear_seq+0x2d/0x40 [ 221.922183] [ 221.922184] Memory state around the buggy address: [ 221.922185] ffffffffba51da80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 221.922187] ffffffffba51db00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 221.922188] >ffffffffba51db80: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 [ 221.922189] ^ [ 221.922190] ffffffffba51dc00: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 [ 221.922191] ffffffffba51dc80: f9 f9 f9 f9 01 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 [ 221.922193] ================================================================== [ 221.922194] Disabling lock debugging due to kernel taint [ 221.922196] ,task=memcg_test_1,pid=11280,uid=0 [ 221.922205] Memory cgroup out of memory: Killed process 11280 Link: https://lore.kernel.org/r/CA+G9fYt46oC7-BKryNDaaXPJ9GztvS2cs_7GjYRjanRi4+ryCQ@mail.gmail.com Fixes: 4cfc7258f876a7feba673ac ("printk: ringbuffer: add finalization/extension support") Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Reviewed-by: John Ogness <john.ogness@linutronix.de> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201014175051.GC13775@alley
2020-10-12Merge branch 'printk-rework' into for-linusPetr Mladek6-577/+3042
2020-10-05printk: Use fallthrough pseudo-keywordGustavo A. R. Silva1-1/+1
Replace /* FALL THRU */ comment with the new pseudo-keyword macro fallthrough[1]. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20201002224627.GA30475@embeddedor
2020-09-30printk: reduce setup_text_buf size to LOG_LINE_MAXJohn Ogness1-1/+1
@setup_text_buf only copies the original text messages (without any prefix or extended text). It only needs to be LOG_LINE_MAX in size. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200930090134.8723-3-john.ogness@linutronix.de
2020-09-30printk: avoid and/or handle record truncationJohn Ogness3-4/+19
If a reader provides a buffer that is smaller than the message text, the @text_len field of @info will have a value larger than the buffer size. If readers blindly read @text_len bytes of data without checking the size, they will read beyond their buffer. Add this check to record_print_text() to properly recognize when such truncation has occurred. Add a maximum size argument to the ringbuffer function to extend records so that records can not be created that are larger than the buffer size of readers. When extending records (LOG_CONT), do not extend records beyond LOG_LINE_MAX since that is the maximum size available in the buffers used by consoles and syslog. Fixes: f5f022e53b87 ("printk: reimplement log_cont using record extension") Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200930090134.8723-2-john.ogness@linutronix.de
2020-09-22printk: remove dict ringJohn Ogness3-200/+64
Since there is no code that will ever store anything into the dict ring, remove it. If any future dictionary properties are to be added, these should be added to the struct printk_info. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200918223421.21621-4-john.ogness@linutronix.de
2020-09-22printk: move dictionary keys to dev_printk_infoJohn Ogness4-83/+92
Dictionaries are only used for SUBSYSTEM and DEVICE properties. The current implementation stores the property names each time they are used. This requires more space than otherwise necessary. Also, because the dictionary entries are currently considered optional, it cannot be relied upon that they are always available, even if the writer wanted to store them. These issues will increase should new dictionary properties be introduced. Rather than storing the subsystem and device properties in the dict ring, introduce a struct dev_printk_info with separate fields to store only the property values. Embed this struct within the struct printk_info to provide guaranteed availability. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/87mu1jl6ne.fsf@jogness.linutronix.de
2020-09-22printk: move printk_info into separate arrayJohn Ogness3-71/+133
The majority of the size of a descriptor is taken up by meta data, which is often not of interest to the ringbuffer (for example, when performing state checks). Since descriptors are often temporarily stored on the stack, keeping their size minimal will help reduce stack pressure. Rather than embedding the printk_info into the descriptor, create a separate printk_info array. The index of a descriptor in the descriptor array corresponds to the printk_info with the same index in the printk_info array. The rules for validity of a printk_info match the existing rules for the data blocks: the descriptor must be in a consistent state. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200918223421.21621-2-john.ogness@linutronix.de
2020-09-15printk: reimplement log_cont using record extensionJohn Ogness1-78/+20
Use the record extending feature of the ringbuffer to implement continuous messages. This preserves the existing continuous message behavior. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-7-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: add finalization/extension supportJohn Ogness2-55/+476
Add support for extending the newest data block. For this, introduce a new finalization state (desc_finalized) denoting a committed descriptor that cannot be extended. Until a record is finalized, a writer can reopen that record to append new data. Reopening a record means transitioning from the desc_committed state back to the desc_reserved state. A writer can explicitly finalize a record if there is no intention of extending it. Also, records are automatically finalized when a new record is reserved. This relieves writers of needing to explicitly finalize while also making such records available to readers sooner. (Readers can only traverse finalized records.) Four new memory barrier pairs are introduced. Two of them are insignificant additions (data_realloc:A/desc_read:D and data_realloc:A/data_push_tail:B) because they are alternate path memory barriers that exactly match the purpose, pairing, and context of the two existing memory barrier pairs they provide an alternate path for. The other two new memory barrier pairs are significant additions: desc_reopen_last:A / _prb_commit:B - When reopening a descriptor, ensure the state transitions back to desc_reserved before fully trusting the descriptor data. _prb_commit:B / desc_reserve:D - When committing a descriptor, ensure the state transitions to desc_committed before checking the head ID to see if the descriptor needs to be finalized. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-6-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: change representation of statesJohn Ogness2-32/+27
Rather than deriving the state by evaluating bits within the flags area of the state variable, assign the states explicit values and set those values in the flags area. Introduce macros to make it simple to read and write state values for the state variable. Although the functionality is preserved, the binary representation for the states is changed. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-5-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: clear initial reserved fieldsJohn Ogness2-16/+26
prb_reserve() will set some meta data values and leave others uninitialized (or rather, containing the values of the previous wrap). Simplify the API by always clearing out all the fields. Only the sequence number is filled in. The caller is now responsible for filling in the rest of the meta data fields. In particular, for correctly filling in text and dict lengths. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-4-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: add BLK_DATALESS() macroJohn Ogness1-2/+4
Rather than continually needing to explicitly check @begin and @next to identify a dataless block, introduce and use a BLK_DATALESS() macro. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-3-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: relocate get_data()John Ogness1-58/+58
Move the internal get_data() function as-is above prb_reserve() so that a later change can make use of the static function. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-2-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: avoid memcpy() on state_varJohn Ogness1-2/+7
@state_var is copied as part of the descriptor copying via memcpy(). This is not allowed because @state_var is an atomic type, which in some implementations may contain a spinlock. Avoid using memcpy() with @state_var by explicitly copying the other fields of the descriptor. @state_var is set using atomic set operator before returning. Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914094803.27365-2-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: fix setting state in desc_read()John Ogness1-7/+19
It is expected that desc_read() will always set at least the @state_var field. However, if the descriptor is in an inconsistent state, no fields are set. Also, the second load of @state_var is not stored in @desc_out and so might not match the state value that is returned. Always set the last loaded @state_var into @desc_out, regardless of the descriptor consistency. Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914094803.27365-1-john.ogness@linutronix.de
2020-09-08printk: ringbuffer: support dataless recordsJohn Ogness2-44/+43
With commit 896fbe20b4e2333fb55 ("printk: use the lockless ringbuffer"), printk() started silently dropping messages without text because such records are not supported by the new printk ringbuffer. Add support for such records. Currently dataless records are denoted by INVALID_LPOS in order to recognize failed prb_reserve() calls. Change the ringbuffer to instead use two different identifiers (FAILED_LPOS and NO_LPOS) to distinguish between failed prb_reserve() records and successful dataless records, respectively. Fixes: 896fbe20b4e2333fb55 ("printk: use the lockless ringbuffer") Fixes: https://lkml.kernel.org/r/20200718121053.GA691245@elver.google.com Reported-by: Marco Elver <elver@google.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Cc: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Marco Elver <elver@google.com> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200721132528.9661-1-john.ogness@linutronix.de
2020-09-01Merge branch 'master' into for-nextJiri Kosina4-104/+211
Sync with Linus' branch in order to be able to apply fixups of more recent patches.
2020-08-10kernel: printk: delete repeated words in commentsRandy Dunlap1-2/+2
Drop repeated words "the" in kernel/printk/. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200807033227.8349-1-rdunlap@infradead.org
2020-08-05Merge tag 'printk-for-5.9' of ↵Linus Torvalds1-4/+12
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Herbert Xu made printk header file self-contained. - Andy Shevchenko and Sergey Senozhatsky cleaned up console->setup() error handling. - Andy Shevchenko did some cleanups (e.g. sparse warning) in vsprintf code. - Minor documentation updates. * tag 'printk-for-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: lib/vsprintf: Force type of flags value for gfp_t lib/vsprintf: Replace custom spec to print decimals with generic one lib/vsprintf: Replace hidden BUILD_BUG_ON() with static_assert() printk: Make linux/printk.h self-contained doc:kmsg: explicitly state the return value in case of SEEK_CUR Replace HTTP links with HTTPS ones: vsprintf hvc: unify console setup naming console: Fix trivia typo 'change' -> 'chance' console: Propagate error code from console ->setup() tty: hvc: Return proper error code from console ->setup() hook serial: sunzilog: Return proper error code from console ->setup() hook serial: sunsab: Return proper error code from console ->setup() hook mips: Return proper error code from console ->setup() hook
2020-08-04Merge branch 'for-5.9-console-return-codes' into for-linusPetr Mladek1-4/+4
2020-07-13doc:kmsg: explicitly state the return value in case of SEEK_CURBruno Meneguele1-0/+8
The commit 625d3449788f ("Revert "kernel/printk: add kmsg SEEK_CUR handling"") reverted a change done to the return value in case a SEEK_CUR operation was performed for kmsg buffer based on the fact that different userspace apps were handling the new return value (-ESPIPE) in different ways, breaking them. At the same time -ESPIPE was the wrong decision because kmsg /does support/ seek() but doesn't follow the "normal" behavior userspace is used to. Because of that and also considering the time -EINVAL has been used, it was decided to keep this way to avoid more userspace breakage. This patch adds an official statement to the kmsg documentation pointing to the current return value for SEEK_CUR, -EINVAL, thus userspace libraries and apps can refer to it for a definitive guide on what to expect. Signed-off-by: Bruno Meneguele <bmeneg@redhat.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200710174423.10480-1-bmeneg@redhat.com
2020-07-10printk: use the lockless ringbufferJohn Ogness1-447/+493
Replace the existing ringbuffer usage and implementation with lockless ringbuffer usage. Even though the new ringbuffer does not require locking, all existing locking is left in place. Therefore, this change is purely replacing the underlining ringbuffer. Changes that exist due to the ringbuffer replacement: - The VMCOREINFO has been updated for the new structures. - Dictionary data is now stored in a separate data buffer from the human-readable messages. The dictionary data buffer is set to the same size as the message buffer. Therefore, the total required memory for both dictionary and message data is 2 * (2 ^ CONFIG_LOG_BUF_SHIFT) for the initial static buffers and 2 * log_buf_len (the kernel parameter) for the dynamic buffers. - Record meta-data is now stored in a separate array of descriptors. This is an additional 72 * (2 ^ (CONFIG_LOG_BUF_SHIFT - 5)) bytes for the static array and 72 * (log_buf_len >> 5) bytes for the dynamic array. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200709132344.760-5-john.ogness@linutronix.de
2020-07-10Revert "printk: lock/unlock console only for new logbuf entries"John Ogness1-7/+3
This reverts commit 3ac37a93fa9217e576bebfd4ba3e80edaaeb2289. This optimization will not apply once the transition to a lockless printk is complete. Rather than porting this optimization through the transition only to remove it anyway, just revert it now to simplify the transition. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200709132344.760-4-john.ogness@linutronix.de
2020-07-10printk: add lockless ringbufferJohn Ogness3-0/+2087
Introduce a multi-reader multi-writer lockless ringbuffer for storing the kernel log messages. Readers and writers may use their API from any context (including scheduler and NMI). This ringbuffer will make it possible to decouple printk() callers from any context, locking, or console constraints. It also makes it possible for readers to have full access to the ringbuffer contents at any time and context (for example from any panic situation). The printk_ringbuffer is made up of 3 internal ringbuffers: desc_ring: A ring of descriptors. A descriptor contains all record meta data (sequence number, timestamp, loglevel, etc.) as well as internal state information about the record and logical positions specifying where in the other ringbuffers the text and dictionary strings are located. text_data_ring: A ring of data blocks. A data block consists of an unsigned long integer (ID) that maps to a desc_ring index followed by the text string of the record. dict_data_ring: A ring of data blocks. A data block consists of an unsigned long integer (ID) that maps to a desc_ring index followed by the dictionary string of the record. The internal state information of a descriptor is the key element to allow readers and writers to locklessly synchronize access to the data. Co-developed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200709132344.760-3-john.ogness@linutronix.de
2020-06-25console: Fix trivia typo 'change' -> 'chance'Andy Shevchenko1-1/+1
I bet the word 'chance' has to be used in 'had a chance to be called', but, alas, I'm not native speaker... Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200618164751.56828-7-andriy.shevchenko@linux.intel.com
2020-06-25console: Propagate error code from console ->setup()Andy Shevchenko1-3/+3
Since console ->setup() hook returns meaningful error codes, propagate it to the caller of try_enable_new_console(). Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200618164751.56828-6-andriy.shevchenko@linux.intel.com
2020-06-22Revert "kernel/printk: add kmsg SEEK_CUR handling"Jason A. Donenfeld1-10/+0
This reverts commit 8ece3b3eb576a78d2e67ad4c3a80a39fa6708809. This commit broke userspace. Bash uses ESPIPE to determine whether or not the file should be read using "unbuffered I/O", which means reading 1 byte at a time instead of 128 bytes at a time. I used to use bash to read through kmsg in a really quite nasty way: while read -t 0.1 -r line 2>/dev/null || [[ $? -ne 142 ]]; do echo "SARU $line" done < /dev/kmsg This will show all lines that can fit into the 128 byte buffer, and skip lines that don't. That's pretty awful, but at least it worked. With this change, bash now tries to do 1-byte reads, which means it skips all the lines, which is worse than before. Now, I don't really care very much about this, and I'm already look for a workaround. But I did just spend an hour trying to figure out why my scripts were broken. Either way, it makes no difference to me personally whether this is reverted, but it might be something to consider. If you declare that "trying to read /dev/kmsg with bash is terminally stupid anyway," I might be inclined to agree with you. But do note that bash uses lseek(fd, 0, SEEK_CUR)==>ESPIPE to determine whether or not it's reading from a pipe. Cc: Bruno Meneguele <bmeneg@redhat.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-12Merge tag 'printk-for-5.8-kdb-nmi' of ↵Linus Torvalds2-13/+8
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk fix from Petr Mladek: "One more printk change for 5.8: make sure that messages printed from KDB context are redirected to KDB console handlers. It did not work when KDB interrupted NMI or printk_safe contexts. Arm people started hitting this problem more often recently. I forgot to add the fix into the previous pull request by mistake" * tag 'printk-for-5.8-kdb-nmi' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk/kdb: Redirect printk messages into kdb in any context
2020-06-11printk/kdb: Redirect printk messages into kdb in any contextPetr Mladek2-13/+8
kdb has to get messages on consoles even when the system is stopped. It uses kdb_printf() internally and calls console drivers on its own. It uses a hack to reuse an existing code. It sets "kdb_trap_printk" global variable to redirect even the normal printk() into the kdb_printf() variant. The variable "kdb_trap_printk" is checked in printk_default() and it is ignored when printk is redirected to printk_safe in NMI context. Solve this by moving the check into printk_func(). It is obvious that it is not fully safe. But it does not make things worse. The console drivers are already called in this context by db_printf() direct calls. Reported-by: Sumit Garg <sumit.garg@linaro.org> Tested-by: Sumit Garg <sumit.garg@linaro.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200520102233.GC3464@linux-b0ei
2020-06-04Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextLinus Torvalds1-1/+1
Pull networking updates from David Miller: 1) Allow setting bluetooth L2CAP modes via socket option, from Luiz Augusto von Dentz. 2) Add GSO partial support to igc, from Sasha Neftin. 3) Several cleanups and improvements to r8169 from Heiner Kallweit. 4) Add IF_OPER_TESTING link state and use it when ethtool triggers a device self-test. From Andrew Lunn. 5) Start moving away from custom driver versions, use the globally defined kernel version instead, from Leon Romanovsky. 6) Support GRO vis gro_cells in DSA layer, from Alexander Lobakin. 7) Allow hard IRQ deferral during NAPI, from Eric Dumazet. 8) Add sriov and vf support to hinic, from Luo bin. 9) Support Media Redundancy Protocol (MRP) in the bridging code, from Horatiu Vultur. 10) Support netmap in the nft_nat code, from Pablo Neira Ayuso. 11) Allow UDPv6 encapsulation of ESP in the ipsec code, from Sabrina Dubroca. Also add ipv6 support for espintcp. 12) Lots of ReST conversions of the networking documentation, from Mauro Carvalho Chehab. 13) Support configuration of ethtool rxnfc flows in bcmgenet driver, from Doug Berger. 14) Allow to dump cgroup id and filter by it in inet_diag code, from Dmitry Yakunin. 15) Add infrastructure to export netlink attribute policies to userspace, from Johannes Berg. 16) Several optimizations to sch_fq scheduler, from Eric Dumazet. 17) Fallback to the default qdisc if qdisc init fails because otherwise a packet scheduler init failure will make a device inoperative. From Jesper Dangaard Brouer. 18) Several RISCV bpf jit optimizations, from Luke Nelson. 19) Correct the return type of the ->ndo_start_xmit() method in several drivers, it's netdev_tx_t but many drivers were using 'int'. From Yunjian Wang. 20) Add an ethtool interface for PHY master/slave config, from Oleksij Rempel. 21) Add BPF iterators, from Yonghang Song. 22) Add cable test infrastructure, including ethool interfaces, from Andrew Lunn. Marvell PHY driver is the first to support this facility. 23) Remove zero-length arrays all over, from Gustavo A. R. Silva. 24) Calculate and maintain an explicit frame size in XDP, from Jesper Dangaard Brouer. 25) Add CAP_BPF, from Alexei Starovoitov. 26) Support terse dumps in the packet scheduler, from Vlad Buslov. 27) Support XDP_TX bulking in dpaa2 driver, from Ioana Ciornei. 28) Add devm_register_netdev(), from Bartosz Golaszewski. 29) Minimize qdisc resets, from Cong Wang. 30) Get rid of kernel_getsockopt and kernel_setsockopt in order to eliminate set_fs/get_fs calls. From Christoph Hellwig. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2517 commits) selftests: net: ip_defrag: ignore EPERM net_failover: fixed rollback in net_failover_open() Revert "tipc: Fix potential tipc_aead refcnt leak in tipc_crypto_rcv" Revert "tipc: Fix potential tipc_node refcnt leak in tipc_rcv" vmxnet3: allow rx flow hash ops only when rss is enabled hinic: add set_channels ethtool_ops support selftests/bpf: Add a default $(CXX) value tools/bpf: Don't use $(COMPILE.c) bpf, selftests: Use bpf_probe_read_kernel s390/bpf: Use bcr 0,%0 as tail call nop filler s390/bpf: Maintain 8-byte stack alignment selftests/bpf: Fix verifier test selftests/bpf: Fix sample_cnt shared between two threads bpf, selftests: Adapt cls_redirect to call csum_level helper bpf: Add csum_level helper for fixing up csum levels bpf: Fix up bpf_skb_adjust_room helper's skb csum setting sfc: add missing annotation for efx_ef10_try_update_nic_stats_vf() crypto/chtls: IPv6 support for inline TLS Crypto/chcr: Fixes a coccinile check error Crypto/chcr: Fixes compilations warnings ...
2020-06-01Merge tag 'core-rcu-2020-06-01' of ↵Linus Torvalds2-7/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The RCU updates for this cycle were: - RCU-tasks update, including addition of RCU Tasks Trace for BPF use and TASKS_RUDE_RCU - kfree_rcu() updates. - Remove scheduler locking restriction - RCU CPU stall warning updates. - Torture-test updates. - Miscellaneous fixes and other updates" * tag 'core-rcu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (103 commits) rcu: Allow for smp_call_function() running callbacks from idle rcu: Provide rcu_irq_exit_check_preempt() rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter() rcu: Provide __rcu_is_watching() rcu: Provide rcu_irq_exit_preempt() rcu: Make RCU IRQ enter/exit functions rely on in_nmi() rcu/tree: Mark the idle relevant functions noinstr x86: Replace ist_enter() with nmi_enter() x86/mce: Send #MC singal from task work x86/entry: Get rid of ist_begin/end_non_atomic() sched,rcu,tracing: Avoid tracing before in_nmi() is correct sh/ftrace: Move arch_ftrace_nmi_{enter,exit} into nmi exception lockdep: Always inline lockdep_{off,on}() hardirq/nmi: Allow nested nmi_enter() arm64: Prepare arch_nmi_enter() for recursion printk: Disallow instrumenting print_nmi_enter() printk: Prepare for nested printk_nmi_enter() rcutorture: Convert ULONG_CMP_LT() to time_before() torture: Add a --kasan argument torture: Save a few lines by using config_override_param initially ...
2020-06-01Merge tag 'printk-for-5.8' of ↵Linus Torvalds2-49/+97
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Benjamin Herrenschmidt solved a problem with non-matched console aliases by first checking consoles defined on the command line. It is a more conservative approach than the previous attempts. - Benjamin also made sure that the console accessible via /dev/console always has CON_CONSDEV flag. - Andy Shevchenko added the %ptT modifier for printing struct time64_t. It extends the existing %ptR handling for struct rtc_time. - Bruno Meneguele fixed /dev/kmsg error value returned by unsupported SEEK_CUR. - Tetsuo Handa removed unused pr_cont_once(). ... and a few small fixes. * tag 'printk-for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: Remove pr_cont_once() printk: handle blank console arguments passed in. kernel/printk: add kmsg SEEK_CUR handling printk: Fix a typo in comment "interator"->"iterator" usb: pulse8-cec: Switch to use %ptT ARM: bcm2835: Switch to use %ptT lib/vsprintf: Print time64_t in human readable format lib/vsprintf: update comment about simple_strto<foo>() functions printk: Correctly set CON_CONSDEV even when preferred console was not registered printk: Fix preferred console selection with multiple matches printk: Move console matching logic into a separate function printk: Convert a use of sprintf to snprintf in console_unlock
2020-06-01Merge branch 'for-5.8' into for-linusPetr Mladek3-32/+84
2020-06-01Merge branch 'for-5.7-preferred-console' into for-linusPetr Mladek2-44/+79
2020-05-30printk: Introduce kmsg_dump_reason_str()Kees Cook1-0/+17
The pstore subsystem already had a private version of this function. With the coming addition of the pstore/zone driver, this needs to be shared. As it really should live with printk, move it there instead. Link: https://lore.kernel.org/lkml/20200515184434.8470-4-keescook@chromium.org/ Acked-by: Petr Mladek <pmladek@suse.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Kees Cook <keescook@chromium.org>
2020-05-30printk: honor the max_reason field in kmsg_dumperPavel Tatashin1-4/+11
kmsg_dump() allows to dump kmesg buffer for various system events: oops, panic, reboot, etc. It provides an interface to register a callback call for clients, and in that callback interface there is a field "max_reason", but it was getting ignored when set to any "reason" higher than KMSG_DUMP_OOPS unless "always_kmsg_dump" was passed as kernel parameter. Allow clients to actually control their "max_reason", and keep the current behavior when "max_reason" is not set. Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Link: https://lore.kernel.org/lkml/20200515184434.8470-3-keescook@chromium.org/ Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Kees Cook <keescook@chromium.org>
2020-05-22printk: handle blank console arguments passed in.Shreyas Joshi1-0/+3
If uboot passes a blank string to console_setup then it results in a trashed memory. Ultimately, the kernel crashes during freeing up the memory. This fix checks if there is a blank parameter being passed to console_setup from uboot. In case it detects that the console parameter is blank then it doesn't setup the serial device and it gracefully exits. Link: https://lore.kernel.org/r/20200522065306.83-1-shreyas.joshi@biamp.com Signed-off-by: Shreyas Joshi <shreyas.joshi@biamp.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> [pmladek@suse.com: Better format the commit message and code, remove unnecessary brackets.] Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-05-21kernel/printk: add kmsg SEEK_CUR handlingBruno Meneguele1-0/+10
Userspace libraries, e.g. glibc's dprintf(), perform a SEEK_CUR operation over any file descriptor requested to make sure the current position isn't pointing to junk due to previous manipulation of that same fd. And whenever that fd doesn't have support for such operation, the userspace code expects -ESPIPE to be returned. However, when the fd in question references the /dev/kmsg interface, the current kernel code state returns -EINVAL instead, causing an unexpected behavior in userspace: in the case of glibc, when -ESPIPE is returned it gets ignored and the call completes successfully, while returning -EINVAL forces dprintf to fail without performing any action over that fd: if (_IO_SEEKOFF (fp, (off64_t)0, _IO_seek_cur, _IOS_INPUT|_IOS_OUTPUT) == _IO_pos_BAD && errno != ESPIPE) return NULL; With this patch we make sure to return the correct value when SEEK_CUR is requested over kmsg and also add some kernel doc information to formalize this behavior. Link: https://lore.kernel.org/r/20200317103344.574277-1-bmeneg@redhat.com Cc: linux-kernel@vger.kernel.org Cc: rostedt@goodmis.org, Cc: David.Laight@ACULAB.COM Signed-off-by: Bruno Meneguele <bmeneg@redhat.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-05-21printk: Fix a typo in comment "interator"->"iterator"Ethon Paul1-2/+2
There is a typo in comment, fix it. Signed-off-by: Ethon Paul <ethp@qq.com> Cc: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-05-19printk: Disallow instrumenting print_nmi_enter()Peter Zijlstra1-2/+3
It happens early in nmi_enter(), no tracing, probing or other funnies allowed. Specifically as nmi_enter() will be used in do_debug(), which would cause recursive exceptions when kprobed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134101.139720912@linutronix.de
2020-05-19printk: Prepare for nested printk_nmi_enter()Petr Mladek2-5/+7
There is plenty of space in the printk_context variable. Reserve one byte there for the NMI context to be on the safe side. It should never overflow. The BUG_ON(in_nmi() == NMI_MASK) in nmi_enter() will trigger much earlier. Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134100.681374113@linutronix.de
2020-05-18printk: fix global commentRandy Dunlap1-1/+1
Fix typo/spello. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-04-27sysctl: pass kernel pointers to ->proc_handlerChristoph Hellwig1-1/+1
Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-04-10printk: queue wake_up_klogd irq_work only if per-CPU areas are readySergey Senozhatsky3-10/+40
printk_deferred(), similarly to printk_safe/printk_nmi, does not immediately attempt to print a new message on the consoles, avoiding calls into non-reentrant kernel paths, e.g. scheduler or timekeeping, which potentially can deadlock the system. Those printk() flavors, instead, rely on per-CPU flush irq_work to print messages from safer contexts. For same reasons (recursive scheduler or timekeeping calls) printk() uses per-CPU irq_work in order to wake up user space syslog/kmsg readers. However, only printk_safe/printk_nmi do make sure that per-CPU areas have been initialised and that it's safe to modify per-CPU irq_work. This means that, for instance, should printk_deferred() be invoked "too early", that is before per-CPU areas are initialised, printk_deferred() will perform illegal per-CPU access. Lech Perczak [0] reports that after commit 1b710b1b10ef ("char/random: silence a lockdep splat with printk()") user-space syslog/kmsg readers are not able to read new kernel messages. The reason is printk_deferred() being called too early (as was pointed out by Petr and John). Fix printk_deferred() and do not queue per-CPU irq_work before per-CPU areas are initialized. Link: https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/ Reported-by: Lech Perczak <l.perczak@camlintechnologies.com> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Tested-by: Jann Horn <jannh@google.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: John Ogness <john.ogness@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-18printk: Correctly set CON_CONSDEV even when preferred console was not registeredBenjamin Herrenschmidt1-0/+2
CON_CONSDEV flag was historically used to put/keep the preferred console first in console_drivers list. Where the preferred console is the last on the command line. The ordering is important only when opening /dev/console: + tty_kopen() + tty_lookup_driver() + console_device() The flag was originally an implementation detail. But it was later made accessible from userspace via /proc/consoles. It was used, for example, by the tool "showconsole" to show the real tty accessible via /dev/console, see https://github.com/bitstreamout/showconsole Now, the current code sets CON_CONSDEV only for the preferred console or when a fallback console is added. The flag is not set when the preferred console is defined on the command line but it is not registered from some reasons. Simple solution is to set CON_CONSDEV flag for the first registered console. It will work most of the time because: + Most real consoles have console->device defined. + Boot consoles are removed in printk_late_init(). + unregister_console() moves CON_CONSDEV flag to the next console. Clean solution would require checking con->device when the preferred console is registered and in unregister_console(). Conclusion: Use the simple solution for now. It is better than the current state and good enough. The clean solution is not worth it. It would complicate the already complicated code without too much gain. Instead the code would deserve a complete rewrite. Link: https://lore.kernel.org/r/20200213095133.23176-4-pmladek@suse.com Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [pmladek@suse.com: Correct reasoning in the commit message, comment update.] Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-02-18printk: Fix preferred console selection with multiple matchesBenjamin Herrenschmidt2-11/+19
In the following circumstances, the rule of selecting the console corresponding to the last "console=" entry on the command line as the preferred console (CON_CONSDEV, ie, /dev/console) fails. This is a specific example, but it could happen with different consoles that have a similar name aliasing mechanism. - The kernel command line has both console=tty0 and console=ttyS0 in that order (the latter with speed etc... arguments). This is common with some cloud setups such as Amazon Linux. - add_preferred_console is called early to register "uart0". In our case that happens from acpi_parse_spcr() on arm64 since the "enable_console" argument is true on that architecture. This causes "uart0" to become entry 0 of the console_cmdline array. Now, because of the above, what happens is: - add_preferred_console is called by the cmdline parsing for tty0 and ttyS0 respectively, thus occupying entries 1 and 2 of the console_cmdline array (since this happens after ACPI SPCR parsing). At that point preferred_console is set to 2 as expected. - When the tty layer kicks in, it will call register_console for tty0. This will match entry 1 in console_cmdline array. It isn't our preferred console but because it's our only console at this point, it will end up "first" in the consoles list. - When 8250 probes the actual serial port later on, it calls register_console for ttyS0. At that point the loop in register_console tries to match it with the entries in the console_cmdline array. Ideally this should match ttyS0 in entry 2, which is preferred, causing it to be inserted first and to replace tty0 as CONSDEV. However, 8250 provides a "match" hook in its struct console, and that hook will match "uart" as an alias to "ttyS". So we match uart0 at entry 0 in the array which is not the preferred console and will not match entry 2 which is since we break out of the loop on the first match. As a result, we don't set CONSDEV and don't insert it first, but second in the console list. As a result, we end up with tty0 remaining first in the array, and thus /dev/console going there instead of the last user specified one which is ttyS0. This tentative fix register_console() to scan first for consoles specified on the command line, and only if none is found, to then scan for consoles specified by the architecture. Link: https://lore.kernel.org/r/20200213095133.23176-3-pmladek@suse.com Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-02-18printk: Move console matching logic into a separate functionBenjamin Herrenschmidt1-40/+65
This moves the loop that tries to match a newly registered console with the command line or add_preferred_console list into a separate helper, in order to be able to call it multiple times in subsequent patches. Link: https://lore.kernel.org/r/20200213095133.23176-2-pmladek@suse.com Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
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