#ifndef _ACKVEC_H #define _ACKVEC_H /* * net/dccp/ackvec.h * * An implementation of Ack Vectors for the DCCP protocol * Copyright (c) 2007 University of Aberdeen, Scotland, UK * Copyright (c) 2005 Arnaldo Carvalho de Melo * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include /* * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN, * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1 * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives * more headroom if Ack Ratio is higher or when the sender acknowledges slowly. * The maximum value is bounded by the u16 types for indices and functions. */ #define DCCPAV_NUM_ACKVECS 2 #define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS) /* Estimated minimum average Ack Vector length - used for updating MPS */ #define DCCPAV_MIN_OPTLEN 16 /* Threshold for coping with large bursts of losses */ #define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8) enum dccp_ackvec_states { DCCPAV_RECEIVED = 0x00, DCCPAV_ECN_MARKED = 0x40, DCCPAV_RESERVED = 0x80, DCCPAV_NOT_RECEIVED = 0xC0 }; #define DCCPAV_MAX_RUNLEN 0x3F static inline u8 dccp_ackvec_runlen(const u8 *cell) { return *cell & DCCPAV_MAX_RUNLEN; } static inline u8 dccp_ackvec_state(const u8 *cell) { return *cell & ~DCCPAV_MAX_RUNLEN; } /** * struct dccp_ackvec - Ack Vector main data structure * * This implements a fixed-size circular buffer within an array and is largely * based on Appendix A of RFC 4340. * * @av_buf: circular buffer storage area * @av_buf_head: head index; begin of live portion in @av_buf * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf * @av_tail_ackno: lowest seqno of acknowledgeable packet recorded in @av_buf * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously) */ struct dccp_ackvec { u8 av_buf[DCCPAV_MAX_ACKVEC_LEN]; u16 av_buf_head; u16 av_buf_tail; u64 av_buf_ackno:48; u64 av_tail_ackno:48; bool av_buf_nonce[DCCPAV_NUM_ACKVECS]; u8 av_overflow:1; struct list_head av_records; }; /** * struct dccp_ackvec_record - Records information about sent Ack Vectors * * These list entries define the additional information which the HC-Receiver * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A. * * @avr_node: the list node in @av_records * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to * @avr_ack_ptr: pointer into @av_buf where this record starts * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent * * The list as a whole is sorted in descending order by @avr_ack_seqno. */ struct dccp_ackvec_record { struct list_head avr_node; u64 avr_ack_seqno:48; u64 avr_ack_ackno:48; u16 avr_ack_ptr; u8 avr_ack_runlen; u8 avr_ack_nonce:1; }; int dccp_ackvec_init(void); void dccp_ackvec_exit(void); struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority); void dccp_ackvec_free(struct dccp_ackvec *av); void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); u16 dccp_ackvec_buflen(const struct dccp_ackvec *av); static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av) { return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail; } /** * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb * @vec: start of vector (offset into skb) * @len: length of @vec * @nonce: whether @vec had an ECN nonce of 0 or 1 * @node: FIFO - arranged in descending order of ack_ackno * * This structure is used by CCIDs to access Ack Vectors in a received skb. */ struct dccp_ackvec_parsed { u8 *vec, len, nonce:1; struct list_head node; }; int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce); void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks); #endif /* _ACKVEC_H */ 55b6672d5a37e (patch) tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /net/rds parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/rds')